• 1 In Switzerland, the Federal Law on Hydropower of 22 December 1916 (LFH, RS 721.80) provides that th (...)

3The idea of the multipurpose use of dam reservoirs clashes with other conceptions of water and energy (Flaminio and Reynard, 2023). The construction of dams and the management of hydropower infrastructure have been highly controversial since the 1920s, and even more since the 1980s (Lehmann, 1998; Hartmann, 2020; Mauch, Reynard and Thorens, 2000). Although, since the 1990s, federal legislation on water protection has introduced environmental flows to reduce the impact of hydroelectric infrastructure on aquatic environments, this law was adopted in a particularly tense political context, especially in the Alpine electricity-producing cantons (Tonka, 2015; Truffer, 2010). Environmental flows have not yet been applied everywhere, not least because, prior to the major licence renewals due to take place in the middle of the 21^st century1 and which will automatically include minimum flows in rivers when new licences will be granted, environmental flows must be set through negotiation between electricity producers and environmental NGOs. In this way, the multipurpose use of dam reservoirs may appear, particularly to conservationists, as a diversification of uses that contradicts the need for more environmental protection of aquatic environments, in particular for environmental flows (Flaminio and Reynard, 2023). This focus on quantifying flows associated with different uses is not specific to the Swiss context, and the sharing of water between different uses (hydroelectric, agricultural, environmental) is the subject of controversy in France, particularly in relation to environmental flows (Gaudin and Fernandez, 2018; Fernandez and Debril, 2016; Fernandez, 2014).

• 2 Translation by the authors from the original citation: « l’existence sur un même espace de différen (...)

8It invites us to embrace ‘territorial pluralism’ (Hoogesteger, Boelens and Baud, 2016), i.e. “the existence in the same space of different visions of what hydrosocial territories are and should be, of how they should be organized and how they should function”2 (Rouillé-Kielo, Le Visage and Flaminio, 2022, p. 3). This concept is particularly effective for critically analyzing power relations in the context of a more general reflection on the interests of different groups of actors and the power they have, and the power arrangements between these groups, particularly in a mountain context, where there is an urgent need to pursue a critical reflection on asymmetrical power relations, sustainability and transitions (Zinzani, 2023; Forget, Bos and Carrizo, 2021). Numerous studies mobilizing the notion of hydrosocial territory have focused on dams (e.g., Götz and Middleton, 2020; Rogers and Wang, 2020; Drapier, Germaine and Lespez, 2023; see also the special issue edited by Boelens, Shah and Bruins, 2019). Much of this research has shown the process of depoliticization and imposition of infrastructures, an imposition that muzzles plural and divergent local territorialities.

• 3 Translation by the authors from the original citation: « des effets de la rencontre entre des visio (...)

9However, the notion of hydrosocial territory has also been criticized for several reasons. According to some authors, studies mobilizing the hydrosocial territory concept have obscured ‘socio-technical details’ relating to water infrastructure (Valadaud and Aubriot, 2019). For this reason, we propose a rich contextualisation on the technical characteristics of the studied infrastructures; such details make it possible to highlight changes in the materiality of infrastructure and in its ‘physicalities’, i.e., the way in which infrastructure is supposed to function (Santoire, Desroche and Garcier, 2021). Moreover, the concept of hydrosocial territories can sometimes lead to a binary reading of power relationships and “the effects of the encounter between divergent territorial visions among groups of stakeholders with distinct interests”3 (Rouillé-Kielo, Le Visage and Flaminio, 2022, p. 2). Indeed, there can be short-term agreements between actors with different territorial visions and interests that can sometimes seem contradictory. Finally, while the notion of hydrosocial territory has primarily been used to describe plural territorial visions at the time when a project is implemented (Rouillé-Kielo, Le Visage and Flaminio, 2022), recent research has shown the importance of analyzing the heritage together with hydrosocial territories; insofar as the entanglement between societies and infrastructure can fluctuate over time (Drapier, Germaine and Lespez, 2023). In addition to documenting case studies, this article uses the concept of hydrosocial territory to contribute to discussions on the limits of the concept and to show how it can be used to analyze complex power relations in mountain areas where issues of transition and adaptation are at the heart of political debates.

• 4 This is the gross production of the dam; the gross production does not take into account the energy (...)
• 5 According to “Energy Statistic Switzerland 2022” (https://www.swissgrid.ch/fr/home/operation/grid-d (...)

12The municipal territory of Nendaz is marked by the presence of the Cleuson hydropower scheme. The Cleuson dam, situated at an altitude of 2179 m, is based on a buttresses (hollow) dam with; its wall is 87 m high. The scheme was built in 1947, gradually brought into service from the winter 1948-1949, and finally completed in 1952. The reservoir, with a capacity of 20 million m³, collects water from the upper reaches of the Printse River (Haute-Printse) and is also supplied by an intake on a tributary of the Printse, the Tortin torrent. Although the Cleuson dam has its own licence dated 7 December 1945, the dam is part of the Grande Dixence hydroelectric complex, a complex with the largest production capacity in Switzerland (ICOLD, 2018). More specifically, the Cleuson Reservoir feeds the Dixence scheme. The Dixence dam was built between 1930 and 1936, and was then flooded by another dam, the Grande Dixence dam completed in 1965. From Cleuson, an underground pumping station at an altitude of 2,119 m directs the water collected in the Cleuson reservoir to a gallery that rises to 2,275 m, and is then redirected to the Puits de Blava (2,247 m) and to Lac des Dix (Dixence scheme). From 1951 to 2013, the water was then channelled through a double penstock to the Chandoline power station (1,748 m drop for a total capacity of 120 MW) before being returned to the Rhône. Between 1993 and 1998, as part of a project to increase the peak hydroelectric output of the Grande Dixence complex, the Cleuson-Dixence project, new tunnels and pipes were built, as well as a new, and completely underground, power station (Bieudron). The Cleuson infrastructure is said to amount for 100 GWh per year4 of the total power production of the Grande Dixence complex, which is around 2 500 GWh per year5. In terms of gross production, Cleuson represents approximately one hundredth of the electricity generated in the canton of Valais, the energy produced in Valais being almost exclusively hydroelectric.

• 6 In the canton of Valais, 100% of the licence rights on the Rhône River (and the Geneva Lake) are he (...)
• 7 As the facility was fully operational in 1952, the licence expires in January 2032.

13The dam licence was granted by the municipalities of Nendaz and Sion6 and by the Canton of Valais to the publicly-owned private company Energie Ouest Suisse (now Alpiq, following a merger between EOS and Atel in 2008) in 1945 for 80 years from the commissioning of the hydroelectric infrastructure7. Towards the end of the 1960s, the municipality of Nendaz asked the operating company whether it would be possible to draw water from the Cleuson reservoir to supplement the municipality’s drinking water supply, particularly in winter, as the number of tourists increases during the ski season. From the 1990s onwards, the municipality also began drawing water from the reservoir to boost artificial snowmaking in several areas of the Nendaz ski area. At present, depending on years, the municipality of Nendaz withdraws between 40 000 and 90 000 m³ of water per year from the Cleuson reservoir for the production and consumption of drinking water, and around 150 000 m³ per year for the production of artificial snow; the water is billed to the commune at price negotiated with the company holding the concession (Alpiq).

• 8 “Placide Moura”, Le bien public, 17/03/1880. Online: https://www.e-newspaperarchives.ch/?a=d&d=LBP1 (...)
• 9 “Chronique littéraire. La vallée perdue”, by Samuel Cornut in the Tribune de Lausanne, Le Confédéré (...)

14Unlike Cleuson, the Hongrin-Léman hydroelectric scheme and the catchment area of the Hongrin River extend over several municipalities. The Hongrin River rises at an altitude of more than 2,400 m in the Vaud Prealps and flows into the Sarine River (Rhine catchment) in the canton of Fribourg, after 21 km (Fig. 1, Tab. 1). In the past, the Hongrin Valley was considered to be “inaccessible”8 , “wild” and “lost”9 , even though the valley was a regional transportation route until the early 19^th century. Today, the river flows through neither villages nor hamlets, but a number of communes in its catchment area and around are characterized by tourism. In addition to hydropower, the catchment area is characterized by livestock farming and military activities.

• 10 Initially, the project did not include a pumping scheme, which was added shortly after the licence (...)

15The Hongrin dam, at an altitude of 1,255 m, was built from 1966 at the mid-point of the Hongrin River in the canton of Vaud; the scheme was brought into service on 1^st October 1971. The dam actually consists of two double-arch dams, a north dam – 95 m high – and a south dam – 123 m high – separated by a rocky promontory. The water from the reservoir, with a capacity of 52 million m³, is turbined in a hydroelectric power station with an installed capacity of 240 MW, located on the shores of Lake Geneva, 878 m below the reservoir, in Veytaux. The turbined water comes from the natural flow towards the reservoir, but also from eight water intakes located in the Vaud Prealps, including outside the Hongrin River catchment, and one water intake from Lake Geneva. This is a pumped storage facility that currently pumps around 300 million m³ of water a year from Lake Geneva up to the Hongrin dam10.

• 11 In the cantons of Fribourg and Vaud, unlike the canton of Valais, the cantons own the surface water (...)
• 12 The company’s shareholders are: Romande Energie SA, Alpiq Suisse SA, Groupe E SA and the City of La (...)

16The infrastructure of the Hongrin-Léman scheme involves water transfers between the Rhine and Rhône catchment areas. Some of the water turbined at Veytaux and returned to Lake Geneva comes from the Rhine catchment, while some of the water from Lake Geneva (Rhône catchment) is likely to be transferred to the Rhine catchment via the inflow to the north dam. For this reason, the facility is subject to a bi-cantonal licence11. The licence was granted by the cantons of Vaud and Fribourg to the Forces Motrices Hongrin-Léman (FMHL12). This company has entrusted the management of hydroelectric production to Alpiq.

• 13 See notes 1 and 6.

19There are major differences between these two hydroelectric schemes, and we are seeking to compare them in order to highlight the singularities (Castree, 2005) and the processes at stake (Baxter, 2016). Although both schemes are located in the Alps, the hydrological and geomorphological contexts are very different, as are the municipalities’ demography and the intensity and diversity of the water uses. The economic and political importance of hydroelectricity is also much greater in the canton of Valais than in the cantons of Vaud and Fribourg; the canton of Valais is the leading canton in terms of hydroelectric power and contributes 30% of the country’s hydroelectric production (Schneider, Buser and Graefe, 2014). Water ownership is organized in different ways. In the canton of Valais, the waters of the Rhône belong to the canton and those of the other rivers belong to the communes; therefore the communes grant the concessions, with the exception of the Rhône (Tab. 1). In the cantons of Vaud and Fribourg, water is part of the cantonal public domain; it is therefore the cantons that grant the licences13.

• 14 For Cleuson, by using “Cleuson” as a keyword in the “Réro Doc - Bibliothèque numérique” online arch (...)

21In order to carry out the comparison, the same type of material was collected for both case studies. Interviews were conducted using the same interview guide, which focused mainly on past, present and future uses and management of the facilities, and included questions on the impacts of the infrastructure and its uses, power relationships between actors, and the spatial perimeters of uses. For Cleuson, 14 semi-structured interviews were conducted with 17 different local actors (politicians, members of municipal and cantonal administrations, representatives of environmental organizations, and water and energy experts). For Hongrin, 14 interviews were conducted with 18 people (members of cantonal administrations, representatives of environmental organizations, and water and energy experts). In addition, research was carried out in digitized archives of the regional daily press14. Finally, archival documents made available by Alpiq were consulted (licence, agreements, brochures).

• 15 In Switzerland, the ‘assemblée primaire’ is the legislative body at municipal level, made up of all (...)
• 16 Here, the text refers to the executive power (municipal council). When the dams were being built, m (...)
• 17 “Les plaintes d’une rivière”, Le Rhône, 11 September 1942, https://doc.rero.ch/record/177191/files/ (...)
• 18 In the name of the Federal Council’s decree of 10 February 1942 aimed at increasing hydroelectric p (...)
• 19 Concession du 14 novembre 1945 des eaux de la Haute-Printze en vue de leur utilisation comme forces (...)
• 20 Decision of the Head of the Intern Departement of the Canton of Valais, 8 May 1950.

23In Nendaz, in 1942, the village’s assembly (assemblée primaire)15 opposed the Cleuson reservoir project, fearing to be deprived of water for agricultural use. The Printse River, across which the Cleuson dam was built, fed (and still feeds today) the bisses, irrigation channels built as early as the Middle Ages to irrigate meadows, vineyards and orchards (Schweizer, 2012). At the time, the construction of the dam was portrayed as a divorce between the river and its population orchestrated by external actors, as expressed in a press article giving voice to the river: “When you’ve always shared in the joys and sorrows of a community, you can’t understand how heartbreaking and painful such a separation is. But I’m not the only one suffering... This spring I heard a confused murmur on my banks. The discontented population, left in complete ignorance by their leaders16, took my side. They, too, saw that those who wanted to abandon me cowardly were thinking only of their personal interests”17. Although in the canton of Valais, the communes owned the water and were in charge of issuing hydropower licenses, the Federal Council ordered the dam to be built on the basis of a decree adopted in the context of wartime economy and aimed at increasing hydroelectric production on a national scale18. The existing water rights associated with the bisses are guaranteed in the license, although no quantity of water is specified19. A pipe and valve were built to return water to the Printse River, but it was stipulated that they would only operate in the event of a shortage. This situation led to a dispute between the operating company and the irrigators shortly after the dam came into operation (Reynard, 2000; Schweizer, 2012); it ended in cantonal arbitration in favour of the irrigators a few years after20. Although the situation has calmed down since (Schweizer, 2012), to date there has been no automated flow monitoring, which some irrigators and the municipality regret.

• 21 “Le ménage fribourgeois”, La Gruyère, 06/11/1947. Online: www.e-newspaperarchives.ch/?a=d&d=LGE1947 (...)

24Because of the water transfers between the Rhine basin (Hongrin River) and the Rhone Basin, the Hongrin-Léman project was contested by the people of Fribourg and controversial from the outset, particularly because of pre-existing hydroelectric uses on the Fribourg side. At the time of its construction, the project is portrayed as being driven by a large city – Lausanne, which lies outside the catchment area and already draws water from it for its drinking water supply (Dirlewanger, 1998) – and “electricity magnates”21 who are seeking to exploit hydroelectric power to the detriment of local agriculture, crafting and fishing:

• 23 “Un premier arrêté du Tribunal fédéral dans l’affaire de l’Hongrin”, La Liberté, 27 February 1948, (...)
• 24 In 1969, FMHL agreed to return part of the energy not produced by the BKW power stations on the Aar (...)

25At the beginning of the year 1948, the canton of Fribourg took the case to the Federal Court, which asked the Federal Council to rule on the matter23. Conciliation led to recognition of the right of the canton of Fribourg to decide on the future of the Hongrin’s waters, even though the dam was to be built in the canton of Vaud. Negotiations ended in 1963, with the participation of Entreprises Électriques Fribourgeoises (EEF, now Groupe E) in the Forces Motrices Hongrin-Léman FMHL company, and with energy supply agreements offered to groups of Fribourg stakeholders (in particular to a sawmill family) to compensate for the loss in local power production and potential hydropower production24.

• 25 1.2 million CHF in 2019; the same year, the total income of the municipality represents approximate (...)
• 26 All interviews were conducted in French and have been translated for the English version of the pap (...)

27The turbulent history of the Cleuson dam was only mentioned by one person interviewed in 2022. Today, the dam is seen above all as an asset on a local scale, it epitomizes the dependence of local communities on colossal infrastructure (Grimault, 2021). This dominant vision can be explained by the economic role of the scheme and the royalties it brings in, which correspond to approximately 3% of the municipality’s income25. The energy it supplies is also perceived as “indigenous” (Interview 13, with a former local councillor, 2022)26.

• 27 The name ‘Super Nendaz’, created in reference to the integrated resorts of the French ‘Plan Neige’, (...)

28As well as being an important part of the local economy and energy production, the scheme is also promoted by the municipality as part of its tourism offer. In the 1970s, the development of winter tourism in the vicinity of the dam was launched; a ski complex called “Super Nendaz” was created, comprising 220 tourism apartments built at 1,734 m, on land belonging to local communities and that had been used for mountain pasture until then27. The regional daily press emphasized the characteristics of the area, highlighting the presence of the Cleuson hydraulic infrastructure:

• 29 For example, the dam was featured on the cover of Nendaz Tourisme’s Summer 2022 press kit. https:// (...)

30Although the road to the dam is closed to traffic, the site is accessible from a number of locations, and there are several walking routes overlooking the lake formed by the dam. Pictures of the reservoir are also used in the resort’s summer tourism promotion29.

• 30 Data for 2021, supplied by the commune of Nendaz.
• 31 These are communally-owned waters that were not granted a license at the time the dam license was g (...)
• 32 Convention sur l’utilisation par la commune de Nendaz du lac de Cleuson comme réservoir d’eau potab (...)

31The municipality now relies on water from the Cleuson reservoir for its drinking water supply and the production of artificial snow; the local entanglement of the scheme has increased over time (Fig. 2). While the water drawn in the reservoir for snowmaking represents only 0.46% of the natural inflow to the Cleuson Reservoir, the inflow from the reservoir accounts for around 20% of the total water used by the ski lift company to produce artificial snow30. The supply of drinking water from the Cleuson reservoir can be explained by the growth in the number of tourist in the resort – the abstraction of water from the dam is higher in winter during the peak tourist season (Interview 5, with an employee of the operating company, 2022) –, but can also be explained by the high quality of the water from the reservoir. According to an elected official from Nendaz, the water from the “Cleuson dam is of very, very good quality, which is why it barely needs to be purified” (Interview 3, 2022). This is also why, in the event of a storm, the municipality of Nendaz prefers drawing water from the dam rather than from other extraction points where water can be more contaminated with sediment (Interview 9, with two people from the public works department of the commune of Nendaz, 2022). Starting in the 2000s, the municipality, in partnership with the operating company, designed a new system (which is not yet in operation) to use the reservoir’s storage capacity in a different way to supply drinking water. This would involve the municipality renting (to Alpiq SA) a volume of one million cubic metres in the Cleuson Reservoir in order to store unlicensed water31. This possibility has been formalized in an agreement32. Compensation will have to be paid for this storage if it represents a financial loss for Alpiq SA, but the storage space is made available free of charge if the reservoir is not at full capacity. However, even if the

• 33 The institutional framework of the multipurpose use of Alpine hydraulic infrastructures, at Swiss a (...)

37This concern is heightened by the fact that, to date, there is no legislation providing a framework for a “multipurpose” management of dam reservoirs, with a hierarchy between different uses, despite the fact that the political debate on the subject is lively, and the Valais cantonal managers and federal authorities have issued recommendations (Flaminio and Reynard, 2022). 33

• 34 “Un demi-siècle d’engagement en faveur du Pays-d’Enhaut”, Antonin Scherrer, Pays D’Enhaut Région, A (...)

38In contrast to the Cleuson development, the vision of the Hongrin Valley as a territory for energy production seems to be shared by most of the players we met. The Hongrin River scheme appears to be poorly integrated at local level. This is not only due to the difference between communal (in the canton of Valais) and cantonal (in the canton of Vaud) water ownership. Other social and economic factors also play a role. The neighbouring communes have not focused their tourism development around the Hongrin Valley or the reservoir. Although the site is used for hiking and camping, and to a lesser extent for swimming and water sports, there is no tourism infrastructure. Shortly after the construction of the Hongrin dam, plans were made to build a small resort on a slope overlooking the reservoir, the Collondaz-Joeurs (or Colonda Jeur) project. The project, promoted by Belgian developers, was abandoned due to local opposition34. Today, the development of spontaneous water sports activities is a source of concern for those working in the hydroelectric sector, who believe that for safety reasons such activities are incompatible with hydroelectric operations:

• 35 https://canons-a-neige.ch/, retrieved 5 june 2025.

45Since the early 2010s, a project to diversify the uses of water from the reservoir dam is being planned to increase the snow cover for the ski areas of Leysin and Les Mosses (at altitudes of between 1,400 and 2,000 m), which are located outside the Hongrin catchment area. To avoid creating a new storage infrastructure from which to produce artificial snow, the project involves building a 17 km pipeline from the Hongrin Reservoir, which would allow pumping and transferring between 160,000 and 200,000 m³ of water per year to an already existing (and small) reservoir situated at the top of the ski area (Interview 2, with an engineer in charge of the project, 2023). The water pumped from the Hongrin dam would be too warm for artificial snow production, which is why the project also includes the creation, at the upstream outlet of the pipe, of a 300 m long ‘artificial river’ fitted with a series of artificial waterfalls so that the water is cooled by the outside air. The project involves returning, during the summer season, some of the water collected by natural flow to the high-altitude reservoir, then sending it through the pipe linking the high-altitude reservoir to the Hongrin Reservoir, while equipping this pipe with a microhydropower turbine. For this reason, the project is presented as “neutral” from an energy production/consumption perspective (Interview 2, 2023). When a public enquiry was conducted in July 2023, more than 200 objections were lodged, and the public opposition was strong 35.

• 37 “Canons à neige, en piste pour la guerre”, Le Temps, 24/07/2023, https://canons-a-neige.ch/wp-conte (...)
• 38 “A project from the past!”, https://canons-a-neige.ch/un-projet-pharaonique/, retrieved 5 june 2025

47The use of water from the Hongrin Reservoir is also put forward, by the mayor of Ormont-Dessous (the municipality in which the Les Mosses ski area is located), as a measure for adapting mountain pastures to climate change: “[the mayor] is also delighted that ‘these pipes will enable us to bring water to our mountain pastures, which is invaluable in the face of the droughts that are coming’”37. Although the loss of energy production from the Hongrin-Léman scheme is not mentioned in these interviews and the hydroelectric company is open to the possibility of drawing water from the reservoir, potential energy loss plays a role in the argument against artificial snow cover. The coalition of opponents, made up of residents of the municipalities concerned by the scheme, farmers, members of environmental organizations and members of the canton of Vaud parliament, openly criticized the project’s energy consumption and the “waste of electricity [...]. in a context of energy shortage, especially in winter”38.

• 40 “Comment l’enneigement est devenu une science”, Le Monde, 15/06/2023.

52However, while multipurpose use seems to allow for the integration of stakeholders other than stakeholders coming from the hydroelectric sector and local stakeholders, it is controversial and raises important questions about power relationships, particularly in the context of climate change. On the one hand, the sustainability – over time and in terms of environmental impact – of this new mode of dam operation may be contested, as at the Hongrin. On the other side of the border, more than fifteen years ago, Marnezy (2008) pointed out that Alpine dams, in particular the Mont-Cenis dam, could acquire an additional interest by supplying water to resorts for the production of artificial snow. Yet projects of this type are now, in some cases, being abandoned: reservoir water temperatures are currently too warm for artificial snow production, as it is the case at Val-Cenis40; infrastructure costs are high, not least because hydroelectric schemes are far from snowmaking sites (17 km in the case of the Hongrin). On the other hand, there is a risk that multipurpose use will push the issue of environmental flows and environmental measures to the backburner in a context where we are seeing both a boom in hydropower dams (Fletcher, 2010; Ahlers et al, 2015) and large hydraulic infrastructures (Birkenholtz, 2023), and an evolution in terms of discourse, such infrastructure being presented as interesting in terms of river management (Santoire, Desroche and Garcier, 2021) .