Comité Français des Barrages et Réservoirs

Legislation, regulation

The rules hereunder are a quick summary of the French regulation concerning dams. For a more detail report, please refer to the ad-hoc page of the European club ofICOLD

A Basic Legal Framework

According to legal point of view, the owner of a dam is responsible for any damage that the dams, directly or not, can create in case of a problem, incident, failure or during normal operation. The general obligations of the owner are defined in few laws, especially a law on water, and laws and decrees for public safety.

The authority takes also his part to guarantee the general public safety and, for that, the authority (French government and its representatives) supervises the action of the owner for dam safety. For some dams (industrial ones) there is also a control of the administration due to the concession system.

The French regulation was modified in 2015 (decree of 12th May 2015). All the regulations can be found in “Environment Code” State of art is the main guide for the projects of new dams or the checking of the safety of existing dams.

B Basic Information

1. Dams subjected to the regulation

According to the law on water, an authorisation by the administration is needed before construction of a dam whatever its height may be. For that authorisation, a technical file is presented by the owner.

The French regulation distributes the dams into three classes (A, B and C) according to the height H of the dam above ground level and the normal volume V of the reservoir. The index C is so calculated :

C =H^{2} x \sqrt{V} where H is in meter and V in millions of cubic meters

  • Class A : dams with H above or equal to 20m and with C above or equal to 1500.
  • Class B : dams not in class A and with H between 10m and 20m and with C above or equal to 200.
  • Class C : dams following one of the 2 conditions :
    • not in class A and B and with H higher than 5m and C above or equal to 20
    • not in class A,B and with H higher than 2m and V> 50000 m3 and with at least one inhabitant within 400m downstream of the dam.

When this is imposed by a special level of risk, the authorities can modify the class of a dam. Furthermore, dams higher than 20 m and with a reservoir above 15,000,000 m3 (and other dams when needed) are subjected to a regulation for emergency planning.

There are about 220 dams of class A, 420 of class B, 2000 dams of class C and several dozens of thousands of dams not classified but with H above 2m.

2/ Entities concerned

a) Administrative organisation
The Ministry of Ecology, Sustainable Development and Energy (MEDDE - has the responsibility for the safety of dams.

An ad hoc committee with highly qualified and independent experts gives an opinion on projects concerning new dams or repair of dams higher than 20 m above the ground level. Its opinion is also required for every subject of general interest.

The inspection of the administration is organised at a regional level in so-called Regional Direction of Ecology, Planning, Housing (DREAL, in French). The civil defence prepares the emergency plans associated with highest dams.

b) Owners
Some companies own a great number of dams (especially Electricité de France) ; however there are many small owners (manufacturers, cities, unions of farming concerns,...).

c) Civil engineers
Since 2010, there is an official procedure for qualification of engineering consulting firms dealing with dams. The ministry delivers an agreement for specific activities defined by the Environment Code.

3/ Dam projects

There are not yet definite rules for the design calculations of dams (loadings, resistance,...). It is planned to publish a new version of the legislation with some official rules for loadings.

The projects involving the highest dams (more than 20 m above the ground level) are examined by the Standing Technical Committee of Dams. The conclusions of this Committee and the publications of the CFBR (French National Committee on Large Dams - constitute the state of art which creates informal design rules and avoids the heaviness of a regulation.
The projects submitted to the Committee must include a certain number of headings (geology, earthquake, floods, materials, risk assessment...).
Following the examination by the Committee, the files are approved by local authorities or by the ministry.

4/ Construction and first filling

The Standing Technical Committee on Dams gives an opinion about the construction programme of dams higher than 20 m, especially about the programme of first filling and the choice of the construction supervisor.
The administration in charge of the supervision attends the main stages of the works, for instance the acceptance of the excavation level. The modifications of the project that may be necessary during the works must be described in a supplementary file that is approved by the administration.

The first filling is considered a very important stage. The construction supervisor is responsible for the first impounding of the reservoir. For dams with possible effects on public safety, it is compulsory to organize a continuous survey. The programme of monitoring and the programme of filling, which includes intermediate plateau, is approved by administration.

5/ Dams operation

The regulation imposes several prescriptions to the owners of dams, according to the class of the dams :

  • The dams of class A or class B must have a safety review that identifies the various scenarios for dam failure, the probability of these events, the consequences and gravity on people and property. This document is reviewed every ten years for class A, every 15 years for class B.
  • The owner (or the concessionaire) must have a detailed file with all the documents concerning the dam. The operator has a register for all the events, incidents, maintenance activities, etc.
  • The owner or the operator must carry out periodical visual surveys (including detailed technical visits yearly for dams of class A, every 5 years for dams of class B…)
  • The operator must implement suitable monitoring unless the authority accept an exemption.
  • The operating instructions for exceptional events (floods, ...) and surveillance are mandatory.
  • The owner or the operator publishes an annual report of the surveillance, the monitoring and the operation of the dams. Every two years (less frequently for dams under class A), the report includes a detailed analysis of the results given by the monitoring.
  • For dams of class A or B, the regulations imposes a risk assessment study, and a review of this study every ten years. This study must include a general safety review including special detailed inspections.
  • Each event concerning dam safety must be reported to the authority.

The administration inspects the dam every year for class A, every 5years for class B The local service of the administration in charge of the dam keeps up to date a file comprising all the useful documents (final drawings, inspection reports, monitoring reports,...). The administration must formally approve many documents.

6/ Dams rehabilitation

The local authority can impose to the owner a diagnosis of the safety of a dam and impose the repair or rehabilitation works (or safety measures like a lower level in the reservoir, the decommissioning of the dam…). The authority has the power to make the works at the owner’s expense.

7/ Emergency planning

Emergency preparedness plans are required for dams or dikes higher than 20 m above the ground level and with a reservoir volume above 15,000,000 m3. Smaller dams can also have an emergency plan if so decided by the authority.
The plans are prepared according to the results of a risk analysis based on the safety review that are mandatory for this category of dams. This analysis estimates the limits and the delay of the inundation after a failure of the dam. This analysis examines also the risk of earthquake or landslide into the reservoir, and the risk during extreme floods.
The owner (or the concessionaire) must install and maintain at his own expense :

  • technical devices for detection and surveillance (surveillance building, lighting of the downstream face, means of information and communication...).
  • alarm devices for the authorities and for the population (means of communication, sirens within the area reached by the flood fifteen minutes after the failure of the dam).

The population is informed of the measures included in the plan.

Two situations of vigilance and one stage of alarm are defined by the regulation :

  • reinforced vigilance
  • serious worry
  • alarm (activation of the sirens and information of the authorities).

The sirens are tested every three months.