The Montpezat hydroelectric complex: an ingenious infrastructure
The Montpezat hydroelectric complex, located between the Loire and Ardèche rivers, was built (1947-1954) to deal with peaks in energy consumption. The water is captured only a few kilometres from the source of the Loire at an altitude of more than 1000 metres in the reservoirs of 3 dams (Lapalisse, Gage, and Veyradère) and in the natural lake of Issarlès. It is turbined in the Montpezat powerplant after a fall of 635 metres towards the Ardèche basin. A 17.5 km long gallery links the three dams and the lake, followed by a 1.4 km long penstock that brings the water to the turbines.
more information on the functioning and the structures that make up the Montpezat complex
A “New Montpezat” for a better water sharing !
Classified as strategic in terms of installed power (138MW), the structure will reach the end of its concession in 2029. The process of renewing the concession will therefore start very soon.
Beyond the energy aspect, water sharing is an issue. The only question of the energy of the structure has not been relevant for a long time, as the structure already provides low-water support for the Ardèche in summer. The construction of new solidarities between the Ardèche and the Haute Loire is an essential subject in the context of climate change, which foresees up to 25% less water. Given the new water-related issues in the regions and the potential uses of the structure, the public debate must take its full place as soon as possible to make proposals to improve the complex in the light of current and future challenges.
This case of water transfer between basins, approximately 220 million m3 each year from the Loire basin to the Rhône basin, is unique in Europe. However, in view of climate change and the increase in droughts, this could no longer be an isolated case. The approach and the reflection we wish to carry out could thus feed into future cases.
Questions and issues for discussion
The current management does not satisfy the various stakeholders in the Loire and Ardèche, EDF and the State, who do not share the same vision and the same interests for the use of this structure (drinking water, tourist activities, electricity production, agricultural use, biodiversity, etc.) and its impacts on the natural environment. Although an inter-SAGE commission exists between the Loire and the Ardèche, relations between stakeholders are limited. It is time to put people around the table to decide on the use of this hydroelectric structure. The renewal of the Montepzat concession is therefore an opportunity to completely rethink the purpose of the structure and the associated models (Tourism? yes! but which one? Agriculture? yes! but which one?…).
It is necessary to inform about the issues in the Montpezat complex, to recreate a dialogue between the actors, to share the visions and needs of each, and to prioritise them with regard to the issues of the territories, the needs of the natural environment and the trends and developments in the climate and energy context. Through the renewal of the concession of the Montpezat complex, ERN wishes to inform, raise awareness and prepare citizens for 3 current issues: drought management, water resource sharing and energy production. A possible reconfiguration of the hydraulic complex where the “new Montpezat” could be a flagship project which would better benefit the area of the springs and which would be part of a large and coherent UNESCO biosphere dynamic at the scale of the Loire-Ardèche-Allier “water tower”.
The Montpezat hydroelectric complex in brief
– Commissioning: 1954
– Average annual production: 310 GWh (Montpezat and Pont-de-Veyrières combined)
– Power: 138 MW
– Volume of water diverted from the Loire (Atlantic) to the Ardèche (Mediterranean): 220 million m3 of water/year
Presentation of the complex, EDF 2016 video (french)
Articles, press release, etc
- 2023.03.22 : Eveil de la Haute Loire ” Sécheresse : l’eau de la Loire détournée vers l’Ardèche continue de faire débat“, par Lionel Ciochetto
- 2021.01.24 : Eveil de la Haute Loire ” Il faut revoir le partage de l’eau de la Loire avec l’Ardèche “, par Lionel Ciochetto
- 2021.01.23 : Eveil de la Haute Loire “Avec l’eau de la Loire, on produit de l’électricité sous terre” par Lionel Ciochetto
Brochures, videos, webinars
- 2022. nov. 15: Webinaire organisé par SOS Loire Vivante: Solidarité entre bassins : Combien d‘eau de la Loire pour l’Ardèche ? Qui en décide ? Comment fonctionne le complexe hydro de Montpezat (Ardèche) ? voir le replay, plus d’infos
- 2020, dec. 08 : Webinaire organisé par SOS Loire Vivante : Changement climatique : quel partage de l’eau sur les hauts bassins Loire Allier Ardèche ?, voir le replay et programme
- 2016, février : Vidéo de présentation du fonctionnement du complexe de Montpezat
- 2013, septembre : Mémoguide sur l’aménagement hydroélectrique de Montpoezat, EDF
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