Many Small vs a Few Big: Alternatives to Megadams in the Chilean Patagonia

Purchase PDF
International Rivers
On March 13, 2011, activists gathered at El Manzano on the Río Baker in Patagonia, Chile for the International Day of Action Against Dams and For Rivers.

In recent years, the performance of large dams has been challenged in different regions of the world especially due to their environmental and social impacts. Extensive conversion of land, major alteration of the hydrological systems, and disruption of freshwater ecosystems are some of the identified effects of megadams on natural resources.1 In Chile, the government has recently rejected the ‘HidroAysen’ project, a megadam proposal in the southern territory. The project intended to construct five dams in the Aysen Region with a total flooding area of 5,910 hectares and a transmission line of 2,000 kilometers.2 The likely environmental impact of the project was the subject of a strong dispute between the government and civil society because of the potential hazards imposed on the valuable biodiversity of the Chilean Patagonia.3,4

Yet, the growing energy consumption of Chile has led the government to continue its efforts to find energy sources with low environmental impacts.5 Chile has an enormous hydropower potential estimated at more than 16,000 MW due to its particular geography of mountains and valleys,6 which represents a clear opportunity for future energy policies. Because the implementation of several small-scale hydroelectric schemes (SHS) rather than megadams has not been explored as a possible alternative in Chile, I would like to present a groundbreaking approach comparing large versus small hydropower performance in order to inform present and future water resource management.

Large Dams: The Best Option?


Alejandro Vega
Regions with the highest annual rainfall should be considered for SHS, such as Los Rios, pictured.

International concern about the environmental and social performance of large-scale dams has been increasing since the beginning of the present century. In the year 2000, in its last report, the World Commission on Dams highlighted that the benefits provided by dams to society cannot be compared with the price paid by the environment and disadvantaged groups.7 Biodiversity loss, extensive conversion of land, climate modification, and irreparable alteration of hydrological flows are some of the impacts that large-scale dams have on natural resources.1 Planetary boundaries on biodiversity loss, climate change, and nitrogen cycles have been largely transgressed in the last few years,8 which is another reason why the development of large-scale dams has been challenged. In addition, dams represent a significant flood risk in several regions of the world under threat of natural hazards such as seismic activity.9 In Chile, the ‘HidroAysen’ project was partially approved by the government in 2008 as a possible option to address the increasing energy demand, which is expected to double by 2030.10 With an approximate investment of US$3.2M, the project was supposed to provide a total installed capacity of 2,750 MW by constructing five dams in the Baker and Pascua Rivers.

Yet the large flooding area of the project (5,900 ha) as well as the length of its transmission line (2,000 km) encouraged civil society, scientific groups, and several environmental NGOs to appeal the primary approval of the government.11 Finally, the project was officially rejected in June 2014. In this scenario, the government has started a campaign to boost alternative energy sources with low environmental impact. According to the National Energy Strategy (2012–2030) minihydraulic, wind, biomass, solar, and geothermal energy are the best options for present and future development.5 Considering the geographical characteristics of Chile, each of these renewable energy sources has a special potential to be implemented in different regions: solar and geothermal in the north, biomass and wind in the central valley, and minihydraulic in the southern territory.

Small-scale Hydroelectric Schemes as a Possible Approach

Recently, run-of-river hydropower plants have been implemented in several countries as new alternatives to the exploitation of water resources. Because they do not require water storage or large tracts of land, their environmental impact is almost negligible on land and aquatic ecosystems.12,13,14,15 According to the European Small-Scale Hydropower Association (ESHA), this type of technology does not interfere with the hydrological flows of a basin system due to the low discharge required for their operation, allowing for the conservation of fishery resources.16 Regarding social impacts, run-of-river schemes do not involve land conversion or resettlement issues, the reason why they have the overall support of local communities.17,18 As SHS do not create a disruption on hydrological systems, they do not affect agriculture or irrigation practices.


International Rivers
A window sticker in the town of Caleta Tortel reads “Chilean Patagonia Without Dams.” The town was firmly against the HidroAysen project.

At the economic level, SHS will probably involve a higher investment than large-scale dams. An SHS costs around US$2M per MW of installed capacity versus the value of the ‘HidroAysen’ project,20 which is US$1.2M per MW of installed capacity.2 However, the value of the unique ecosystem services of the Aysen Region is not included in the neoclassic economic equation.

Even though there is no official valuation of these services, it is obvious that both the government and civil society had to prioritize the conservation of the biodiversity of southern Chile. From an ecological economics perspective, human welfare cannot be measured only through economic growth and development, but also should consider the current ecological limits of the planet, allow for fair distribution, and promote an efficient allocation of resources.21,22

The Proposal: Many Small Rather than a Few Big

Considering the environmental, social, and ecologically economic advantages of SHS as well as the recent governmental rejection of the megadam proposals in southern Chile, I would like to introduce the idea of implementing several run-of-river schemes as a possible alternative to the ‘HidroAysen’ project. To achieve this, it would be necessary to analyse the hydraulic potential of the rivers of southern Chile and determine the hydroelectric feasibility of this approach according to the following methodology:

  • Determination of the study site: In order to ensure constant operation of SHS, it is necessary to consider the regions of Chile with the highest rainfall patterns. According to the Meteorological Agency of Chile, the regions with the highest annual average rainfall are the Bio-Bio, Araucania, Los Rios, Los Lagos, and Aysen (see Figure 1).23
  • Identification of hydroelectrical requirements of SHS: There are different classifications of the SHS schemes, but taking into account the significant hydropower potential of Chile as well as the latest available technologies, an adequately installed capacity for SHS corresponds to 50 MW, and the minimum flow for its operation is equal to 13 m3/sec.20,24,25,26,27
  • Analysis of the hydraulic characteristics of the rivers of the study site: To select the rivers of the study site that have enough flow (m3/sec) for the operation of SHS. According to the data available in the Hydrological Report 2014 of the Chilean Water Agency of Chile, there are 61 monitoring stations with a flow rate higher than 13 m3/sec (see Figure 2).28 Each of these monitoring stations represents a different river, except for larger rivers that have more than one monitoring station through its extension. Each of these monitoring stations represents a potential site for the development of SHS.
  • Comparison of the total installed capacity of small and large-scale schemes: The megadam proposal for ‘HidroAysen’ was intended to provide a total installed capacity of 2,750 MW. According to the findings of this report, there are 61 potential sites for the development of SHS. Because each SHS plant can provide an installed capacity of 50 MW, 61 SHS plants can provide a total installed capacity of 3,050 MW, which represent a higher hydroelectric performance than the ‘HidroAysen’ project.

Adapted by the author from the 2014 Water Agency Hydrological Report
Potential sites for SHS development.

Concluding Remarks

For a long time, large-scale hydropower has been considered the best alternative for the exploitation of water resources in Chile. Although large dams have generated many economic and energy benefits for the country’s development, this type of hydropower has caused irreparable damage to the valuable biodiversity of central and southern Chile as well as significant social conflicts. Due to growing environmental awareness in the country, both civil society and the government have recently rejected the ‘HidroAysen’ project, a megadam proposal in the Aysen Region because of its high impact on the natural resources of the proposed construction site.

In order to address this situation, I have introduced a possible alternative for the management of water resources in Chile. According to the findings of this research, several small-scale hydropower schemes (SHS) in Southern Chile can provide even more electricity than the rejected ‘HidroAysen’ project, with a negligible impact on the social and environmental spheres. As mentioned before, the implementation of a number of SHS will probably require a higher investment than the construction of a few large-scale dams under a neoclassic economic approach; yet ecological economics could certainly provide a different perspective through the valuation of the ecosystem services jeopardized by the construction of megadams.


Steffen Sauder
The Río Baker in the Aysen region of southern Chile. The HidroAysen project included proposals for 2 dams on the river.

Considering the current crisis of our ecological support system, it is crucial that the society focuses on a sustainable human well-being rather than just economic growth, incorporating the conservation of the natural capital and allowing social and intergenerational fairness. In this scenario, SHS deployment could represent a feasible environmental, economical, and social alternative for the management of water resources in Chile. Further research is necessary to determine the value of the ecosystem services in southern Chile, and therefore, incorporate this approach in the present and future decision-making arena.

Special thanks to Sara Beavis, Ida Kubiszewski, and Maria Amenabar.