The impacts of large dams, according to reports from the World Commission on Dams (CMR) and the Inter-American Association for the Defense of the Environment - AIDA

The impacts of large dams, according to reports from the World Commission on Dams (CMR) and the Inter-American Association for the Defense of the Environment - AIDA

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By Efrén Diego Domingo

The final report of the CMR presents ample evidence that large dams have failed to produce the electricity offered, supply the required water, or prevent flood damage to the extent predicted by their developers. They also produce serious environmental damage and environmental damage translates into a serious and repeated impact on the human rights of the affected people and communities.

"We don't need your electricity. Electricity will not give us food ...
We need the forests to hunt and gather.
We don't want your prey "
Kayapó woman to a Brazilian civil servant, 1989

a) Speeches for and against dams

What the promoters of the dams say (builders, financiers, governments) is that there are demands for energy, hydroelectric plants provide cheaper energy and are not polluting, generate development, employment, facilitate the electrification of communities, energy to export in the markets, it will bring projects, it will lift people out of poverty ... and a lot of arguments.

Those who oppose these (not necessarily against development, as the former say) point out the adverse impacts of dams, such as the burden of indebtedness, over-cost, displacement and impoverishment of people, the destruction of important ecosystems and fishery resources, and the unequal distribution of costs and benefits. (2)

This has generated confrontations and conflicts between those who urgently need to spend their money on this type of project and those who defend their rights to life, lands, territories, natural resources and dignity. Faced with growing opposition to large dams around the world, the World Bank and the World Conservation Union (IUCN), in May 1998 established the World Commission on Dams (WCD), whose mandate was:

a) reviewing the effectiveness of large dams in driving development and evaluating alternatives for developing water and energy resources, and

b) develop internationally acceptable criteria, guidelines, and standards for the planning, design, diagnosis, construction, operation, monitoring, and dismantling of dams.

To fulfill its mandate and substantiate its report and conclusions, the World Commission on Dams carried out:

a) Detailed studies of 8 large reservoirs on 5 continents and documents evaluating the results of dams in China, India and Russia.

b) 17 thematic reviews on social, environmental, economic and financial aspects; alternatives to dams; different approaches to environmental impact planning and diagnoses.

c) Brief reviews of 125 large dams in 56 countries.

d) Four public hearings in different regions; Y,

e) 950 presentations delivered by interested individuals, groups and institutions.

The WRC report: “Dams and Development: A New Framework for Decision Making”, of 412 pages, came out in November 2002.

b) What were the main conclusions of the report of the World Commission on Dams (WCD)?

The CMR found that, while “dams have made an important and significant contribution to human development, and the benefits derived from them have been considerable. In too many cases an unacceptable and often unnecessary price has been paid to achieve such benefits, especially in social and environmental terms, by displaced people, by downstream communities, by taxpayers and by the natural environment ”(3). It is considered unacceptable to apply a “statement of financial position” (profit and loss) approach to assessing the costs and benefits of large dams, offsetting the losses of one human group with the gains of another - especially in light of existing commitments with human rights and sustainable development.

The final report of the CMR presents ample evidence that large dams have failed to produce the electricity offered, supply the required water, or prevent flood damage to the extent predicted by their developers. Additionally, the report showed that:

1) Large dams have forced 40-80 million people to abandon their homes and lands, with impacts that include extreme economic suffering, the disintegration of their communities, and an increase in their mental and physical health problems. Indigenous, tribal and peasant communities have suffered disproportionately. People who live downstream from reservoirs have also suffered from water-borne diseases and the loss of the natural resources on which they depended for their livelihoods.

2) Large dams cause great environmental damage, including the extinction of many fish and other aquatic species, tremendous losses of forests, wetlands and agricultural land.

3) The benefits of large dams have been mainly for rich people, while the poor have had to bear its costs (4).

c) What were the conclusions of the report: Great Dams in America, Is the cure worse than the disease? of the Inter-American Association for the Defense of the Environment, AIDA?

Through the five case studies (5), the analysis of experiences worldwide, and scientific studies, he found that the most frequent environmental impacts derived from large dams are summarized in:

1. Deterioration of the quality and health of the waters both upstream and downstream due to the artificial modification of the hydrographic basins. Blocking the natural flow causes increases in sedimentation, with accumulation of nutrients and organisms that encourage the proliferation of algae, which can cover the surface of the reservoir and render its water useless for domestic and industrial consumption. Large reservoirs can also produce contamination with toxic substances or bacteria that threaten public health.

2. Degradation of aquatic ecosystems, in fact, large dams are the main physical cause of this degradation. At least 400,000 km2 of the world's most diverse riparian ecosystems have been lost by being flooded to create dams.

3. Impacts to biodiversity, for example, impacts on migratory fish species are very serious due to the construction of large dams in their habitats, because these species require a source of fluid and unobstructed fresh water to be able to breed and spawn.

4. Impacts on climate change due to the increase in the emission of greenhouse gases caused by the decomposition of organic matter flooded by the work. Likewise, climate change could impact the safety and productivity of dams due to drastic changes in rainfall and droughts.

5. Seismic effects that large dams and reservoirs can produce due to the high pressure of the water in the reservoir, which can lubricate tectonic faults and reduce friction between the surfaces of underground rocks (6).

Regarding the violation of international environmental law and human rights, these projects - dams - show that environmental damage results in a serious and repeated impact on the human rights of the affected people and communities. The report continues to demonstrate that these projects ignore the norms of international environmental law and various international standards on the implementation and operation of dams and other large constructions that must be considered when promoting a project. The analysis from international law about the situation of large dams in the region shows the following most important violations:

1. Effects on health, loss of food sources and traditional ways of life. The construction of large dams has documented the destruction of strategic ecosystems essential for biodiversity and for human populations, including forests, wetlands and fertile arable areas. Such impacts can cause the accumulation of toxic sediments such as heavy metals in reservoir waters and groundwater, increased water and insect-borne diseases, irreversible damage to the reproduction and migration cycles of fish, and reduced water available for irrigation. Therefore, dams not only have a direct environmental impact, but also affect quality of life, health, access to food sources and traditional ways of life.

2. Forced displacement. A serious consequence of the construction of large dams is the forced displacement of individuals and entire communities, seriously violating their human rights, particularly the right to free movement, property, housing and adequate compensation. These displacements continue to occur without the implementation of the necessary measures to avoid these consequences, including conducting prior studies, effective consultation processes and timely and effective public participation, and adequate compensation and compensation plans.

3. Comprehensive environmental and social impact assessments. Another of the significant shortcomings of large dam projects that are implemented in an inadequate way is the lack of environmental and social impact assessments (EIA), required according to multiple international norms and standards. Comprehensive EIAs (7) are part of the principles of international environmental law and are included in treaties such as the Convention on Biodiversity. These evaluations are essential to identify, analyze and subsequently reduce or eliminate the possible environmental damage of a project, and therefore, the effects on human rights involved. EIAs are also linked to the right to access information, and the obligation to guarantee all rights universally.

4. Consultation and public participation. An essential requirement that the development of these projects should meet is the implementation of prior and effective consultation processes, with the affected communities and populations and other stakeholders, to allow them a real and informed participation. This is ordered by international norms and standards, in order to guarantee human rights, especially public participation, access to information, as well as other rights that may be violated by large dams, as mentioned. Furthermore, guaranteeing consultation and participation is an essential requirement for the protection of the right to a healthy environment and other human rights that can be affected by environmental degradation. However, this does not happen for the projects analyzed in the region, in which the affected communities are not allowed the opportunity to participate in a real and effective way.

5. Access to information. Free, adequate and timely access to public information is key to guaranteeing the protection of the environment and the participation of affected people in the planning and approval of dams. Without this, participation would not be possible since it is necessary for interested persons to be aware of the risks and consequences associated with the dam for an effective protection of their rights. In addition to being a human right, access to information on large dam projects for affected people and communities is also required by multiple international standards. Thus, the States must have public and effective procedures to access information on licenses, concessions and evaluations carried out, or the reasons why they have not been carried out, and any other type of information relevant to the project.

6. Rights of indigenous and tribal peoples: The construction of large dams frequently affects communities of indigenous and Afro-descendant peoples. There are specific international rights and standards to protect these peoples and the particular cultural relationship that communities enjoy with their traditional territories, including the right to be consulted and to obtain their consent in a free, prior and informed manner, for projects that may affect them (8 ). Despite this, communities are repeatedly denied the possibility of adequate consultation and participation, among other rights. Therefore, it is essential to remember that States have the obligation to respect the rights of these communities when implementing large dams, in accordance with international standards.

7. Criminalization of social protest. In some cases of large dams, there has been harassment of people and communities that defend their rights, including the initiation of judicial processes, the use of force in peaceful protests and threats and even attacks on leaders and individuals of the communities.

These facts have been examined by various organs of international law in cases of large dams and also in other contexts, and are considered criminalization of civil protest, which is contrary to human rights. The increase in these infrastructure projects that do not conform to international standards implies a potential worsening of this situation, due to the increase in new communities affected in defense of their rights and seeking the guarantee of their effective public participation.

d) What do the reports of the World Commission on Dams and the Inter-American Association recommend?

The CRM recommends:

a) No dam should be built without the “demonstrated acceptance” of the affected people, and without the free, prior and informed consent of the affected indigenous and tribal peoples.

b) Complete and participatory diagnoses of people's water and energy needs, as well as different options to meet those needs, should be developed before proceeding with any project.

c) Efforts to maximize the efficiency of existing water and energy systems should be prioritized before building new projects.

d) Periodic participatory reviews of existing reservoirs should be carried out to evaluate elements such as their safety, and the possibility of taking them out of operation and returning, as far as possible, to the current situation prior to construction.

e) Mechanisms should be developed to compensate, or retroactively compensate, those who have been harmed by existing dams, and to restore damaged ecosystems.

The report of the Inter-American Association for the Defense of the Environment recommends that the States:

a) Promote public policies that encourage the efficient use of energy and water, and that encourage the development of truly clean alternative energies that are less harmful than large dams;

b) Comprehensively evaluate current and future projects that involve the construction of large dams, to diagnose possible alternatives to the production of internal energy and the management of water resources;

c) Create and adequately implement procedures that guarantee a timely, comprehensive and effective public participation to communities and interested persons in all stages of planning and implementation of large dam projects, particularly in relation to populations that will be displaced and indigenous communities , tribal and peasant;

d) Require in national legislation that environmental and social impact studies conform to international standards and norms on the subject, and that they be carried out in a rigorous manner by independent entities, which evaluate all cumulative and long-term impacts. project term, including impacts to climate change, ecosystems and local food sources, seismic effects and possible alternatives;

e) Respect, in accordance with the recommendations of international law organizations, the human rights of people who defend rights and the environment, who may be threatened by large dam projects, and recognize the work of these people;

f) Ensure effective, free and timely access to information, documentation and permits related to dam projects at any stage of planning, construction or operation, to any interested person, community or organization, providing mechanisms for easy access and distribution of information;

g) Develop energy projects that are truly necessary, with a focus on human rights and environmental protection, and that consider the benefits and alternatives in the short, medium and long term;

h) Apply current national and international standards and address the recommendations of national and international bodies regarding new and existing projects and implement them effectively, particularly in compliance with the recommendations of the World Commission on Dams on this matter (9).

Efren Diego Domingo


(1) AIDA is an international non-governmental organization with the mission of strengthening the capacity of people to guarantee their individual and collective right to a healthy environment through the development, application and effective compliance of national and international legislation.

(2) Efrén Diego Domingo: Dams, their dark sides and new ways to make decisions:…

(3) Dams and Development: A New Framework for Decision Making. The final report of the World Commission on Dams. Executive Summary, p. xxx.

(4) Aviva Imhof, Susanne Wong, and Peter Bosshard. Citizen's Guide to the World Commission on Dams, published by International Rivers Network / Red Internacional de Ríos, p. 2, Berkeley, California, USA 2002-04-12.…

(5) Yacyretá (Argentina and Paraguay), Rio Madeira (between Bolivia and Brazil), Baba (Ecuador), Chan-75 (Panama) and La Parota (Mexico)

(6) Executive Summary of the AIDA report at:…

(7) For cases related to indigenous peoples and communities, previous studies of social and environmental impact are of utmost importance. The Inter-American Court, in its interpretation judgment of August 12, 2008, case of the Saramaka people v. Suriname, paragraphs 40 and 41 explains “ESIAs are used to assess the possible damage or impact that a development or investment project may have on the property and community in question. The objective of the ESIAs is not only to have some objective measure of the possible impact on the land and people, but also, as indicated in paragraph 133 of the Judgment, to ensure that the members of the Saramaka people are aware of the possible risks, including environmental risks and health, so that they accept the proposed development or investment plan knowingly and voluntarily ”. ESIAs must be carried out in accordance with international standards and good practices in this regard and must respect the traditions and culture of the Saramaka people. (…) ESIAs must be assumed by independent and technically capable entities, under the supervision of the State. One of the factors that the social and environmental impact study should address is the accumulated impact generated by existing projects and those that will be generated by the projects that have been proposed. The best thing about this ruling is that it is binding on all American states.

(8) The right to consultation and prior, free and informed consent to indigenous peoples and communities is recognized in articles 6, 7 and 15 of ILO Convention 169 and article 19 of the United Nations Declaration on the Rights of indigenous peoples. The Inter-American Court of Human Rights (IACHR) in its interpretation judgment in the case of the Saramaka People v. Suriname, dated August 12, 2008, paragraph 17, emphasized: “in the case of large-scale development or investment plans that could affect the integrity of the lands and natural resources of the Saramaka people, the State has the obligation, not only to consult the Saramaka, but also to obtain their free and prior informed consent, according to their customs and traditions ”.

(9) Inter-American Association for the Defense of the Environment. Large Dams in America Is the Cure Worse Than the Disease? Main environmental and human rights consequences and possible alternatives. Page 111, year 2009.

Video: Institutional Video - The Benefits of Dams and Reservoirs - High Quality (July 2022).


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