Updated: The EA online Risk of flooding from reservoirs flood map has been updated to include depth and velocity of flood water as well as the area that it will cover.
Register your reservoir
All reservoirs with a capacity of 25,000 cubic metres or more, that could escape in the event of a dam failure, must be registered with the Environment Agency (EA). These are called large raised reservoirs. They are large raised structures designed or used for collecting and storing water; these structures can include large lakes.
To register your reservoir you will need to provide the:
name of the reservoir
grid reference
name and address of the reservoir owner(s) and/or operator(s)
summary of all certificates issued by panel engineers
type of reservoir (impounding or non-impounding)
date construction was completed
type of dam and dam height
dam top level and top water level
capacity of reservoir
water surface area
name and address of the construction or supervising engineer
date when the next inspection is due
Register your reservoir, or update your information, by emailing reservoirs@environment-agency.gov.uk.
Or write to the EA at:
Reservoir Safety Team
Environment Agency
Manley House
Kestrel Way
Exeter
Devon
EX2 7LQ
You can use these contact details to request access to the public register of large raised reservoirs in England.
Reservoirs that hold less than 25,000 cubic metres of water do not need to be registered with the EA but are subject to safety regulations. These regulations are managed by the Health and Safety Executive and local council.
Building or modifying a reservoir
You must let the EA know if you intend to build, bring back into use or alter a large raised reservoir.
You must also consider whether you need planning permission and an environmental permit.
How reservoirs are regulated
Once registered, the EA will determine whether or not your large raised reservoir is ‘high-risk’. A reservoir is ‘high-risk’ if, in the event of an uncontrolled release of water from the reservoir, human life could be endangered.
If your reservoir is ‘high-risk’, the full regulations will apply.
If your reservoir is ‘not high-risk’ it:
will still need to be registered
won’t be subject to full regulations
It is important that ‘not high-risk’ reservoirs are registered. This is so that their designation can be reviewed if there is a change of circumstance, for example, a downstream development.
Until the EA decide whether or not your large raised reservoir is ‘high-risk’, it will continue to be fully regulated which means you will need to have a supervising engineer appointed and a 10 yearly inspection.
You will be told by the EA of the decision to designate your reservoir as ‘high-risk’, how to challenge it and your right of appeal.
When to appoint a panel engineer
You are required to appoint a panel engineer for large raised reservoirs, including those classed as ‘high-risk’:
during the design and construction of any reservoir with an ‘escapable’ volume greater than 25,000 cubic metres (construction engineer)
where an abandoned reservoir is to be restored and will be brought back into use as a large raised reservoir again (construction engineer)
to supervise the reservoir once built (at all times) and produce a statement once a year (supervising engineer)
to carry out an inspection every 10 years, identify safety work and set you deadlines for the work to be completed (inspecting engineer)
to supervise and certify any recommended measures to be taken in the interests of safety (inspecting engineer)
Reservoirs that have been determined as ‘not high-risk’ only need to appoint a construction engineer during the design and construction, restoration or alteration of the reservoir. Supervising and inspecting engineers are not required.
Appoint a panel engineer
If you have an impounding reservoir (with earth embankment dams blocking the natural flow of a river or drainage from an area) that is ‘high-risk’ you should appoint an engineer from the All reservoirs panel list and/or the Supervising panel engineer list.
If you have a non-impounding reservoir (that does not block the natural flow of a river but is filled by pumping water or by piped inflow) that is ‘high-risk’ you can choose an engineer from the Non-impounding reservoirs list, the All reservoirs panel list and/or the Supervising panel engineer list.
Reservoirs that are covered and contain drinking water are called service reservoirs and are normally owned by water companies. Where a panel engineer is required for these reservoirs they can be chosen from the All reservoirs panel list, the Non-impounding reservoirs list, the Service reservoirs list and/or the Supervising panel engineer list.
The panel engineers listed are qualified civil engineers and are approved by Defra on behalf of the Secretary of State for Environment, Food and Rural Affairs.
Prepare a reservoir flood plan and flood map
A reservoir flood plan sets out how you and the emergency services will respond if there is an uncontrolled release of water from your reservoir.
The plans will include:
an on-site flood plan of essential actions to reduce the potential risk of failure
an off-site flood plan of essential actions to reduce the potential consequence of failure
reservoir flood maps that show the downstream impacts of an uncontrolled release of water
key contacts with emergency services
On-site reservoir flood plan
It is recommended that you produce an on-site reservoir flood plan. Include details of how you will prevent the dam from failing in an emergency and how you will contain and reduce the effects of the failure.
Use the templates and guidance to create your on-site reservoir flood plan.
Off-site reservoir flood plan
Local councils are responsible for coordinating off-site plans for reservoir flooding and ensuring communities are well prepared. Local authorities will work with other members of the Local Resilience Forum to develop these plans.
Off-site plans set out what the emergency services will do to warn and protect people and property if a dam or reservoir could fail.
Reservoir flood maps
The EA have prepared reservoir flood maps to show the impact that an uncontrolled release of water could cause downstream if a dam or reservoir fails.
If your reservoir was registered with the EA in 2009 when these maps were produced you will have received a copy of the reservoir flood map. It will help you with your on-site flood plans. If you registered your reservoir after 2009 it is your responsibility to produce the reservoir flood map for your reservoir.
The EA online risk of flooding from reservoirs map also includes information on the depth and speed of flood water as well as the area that could flood in the unlikely event that a reservoir fails and releases the water it holds.
Local authorities also use these maps to develop off-site reservoir flood plans with their Local Resilience Forums.
Report an incident at your reservoir
If an incident occurs at your ‘high-risk’ reservoir you must contact your supervising engineer and/or an inspecting engineer.
If your reservoir is not ’high-risk’ it is recommended you should seek advice from an inspecting engineer on the approved panel engineer lists.
For all registered large raised reservoirs you have a legal requirement to contact the EA incident hotline on 0800 80 70 60 to report any incident, for example:
overtopping of the dam
a leak
slope instability
cracks in the dam
instrumentation readings
material failure
pollution incident
As soon as the incident is under control you must provide an initial report of the incident to reservoirs@environment-agency.gov.uk or call 01392 442001 (9am-5pm Monday to Friday). Your report must contain:
the date and time of the incident
the location of the reservoir
any facts you consider important
Within one year from the start of the incident you must send the EA a final report using the Post-incident report form.
Information gathered about incidents is used to inform learning and research. The lessons learnt from these incidents are shared with the reservoir industry in an annual report to promote reservoir safety.
Further information
Reservoirs Act 1975
Water Act 2003
Flood and Water Management Act 2010