The Environment Agency has issued guidance reminding all owners of reservoirs in England with a capacity of 25,000 cubic metres or more, that could escape in the event of a dam failure, that they must be registered with the Environment Agency.

The large raised reservoirs can include large lakes, in addition to the water supply reservoirs owned and maintained by the water companies.

Owners will need to provide the following information to register a  reservoir with the Agency:

• 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

Owners are also required to notify the EA of the intention  to build, bring back into use or alter a large raised reservoir and to consider whether planning permission and an environmental permit will be needed.

Environment Agency will designate high-risk reservoirs

Once registered, the EA will determine whether or not the large raised reservoir is ‘high-risk’ – i.e. in the event of an uncontrolled release of water from the reservoir, human life could be endangered. Reservoirs outside the high-risk category will still need to be registered 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 a large raised reservoir is ‘high-risk’, it will continue to be fully regulated and need to have a supervising engineer appointed and a 10 yearly inspection. Owners can challenge the EA over a decision to designate a reservoir as ‘high-risk’and have a right of appeal.

A panel engineer must be appointed in the following circumstances:

• 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 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.

The service reservoirs owned by water companies which are covered and contain drinking water will also require the appointment of panel engineers.

Owners must prepare reservoir flood plan and flood map

Owners must also prepare a reservoir flood plan and flood map setting out how they and the emergency services will respond if there is an uncontrolled release of water from the reservoir.

The plans must 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

The EA has separately prepared reservoir flood maps to show the impact that an uncontrolled release of water could cause downstream if a dam or reservoir fails. If a reservoir was registered with the EA in 2009 when the maps were produced owners will already have received a copy of the reservoir flood map. For reservoirs registered after 2009 it is the owner’s responsibility to produce the reservoir flood map for the reservoir.