São Manoel Dam is operated by the consortium Empresa de Energia São Manoel (EESM), which is formed by the Portuguese company EDP, the state-controlled company Furnas (part of the Eletrobrás group), and the global hydropower giant China Three Gorges, which since 2014 holds one-third of the shares [3][4][6]. 

With a capacity of 746 MW, the plant is one of six recent hydroelectric projects on the Teles Pires river and its tributary Apiacás – the others being Teles Pires Dam, Sinop Dam, Colíder Dam, and the not-yet-opened Foz do Apiacás Dam and Salto Apiacás Dam. The dams also come with plans to develop a navigable waterway for soy export from Mato Grosso to the Atlantic Ocean (‘Hidrovía Teles Pires-Tapajós’), as their creation would allow barges to pass rapids and waterfalls. In total, 43 large dams were recently announced for the entire Tapajós basin (see also related conflicts). As São Manoel Dam, they were often pushed forward by Brazil’s Program for Accelerated Growth (PAC) and increasing energy demand in the region, particularly resulting from economic interests in expanding gold and bauxite mining [7][8][9][10][11].

Since the very first proposals, however, São Manoel Dam has faced critique for its expected adverse impacts on fish and turtles in the river, and its location just 700 meters from the Kayabi Indigenous Territory. This provoked a number of confrontations with the Kayabi, Munduruku, and Apiaká indigenous groups who saw their culture, environmental, and food supply under threat and positioned themselves against hydropower development in the region. Particularly controversial was that the dam was placed on an indigenous sacred site called Dekoka’a (Morro do Macaco, or ‘Monkey Hill’), shortly after construction works at the Teles Pires Dam further upstream had already destroyed the sacred site Karobixexé. This not only harmed indigenous cultures and their cosmology but also involved the removal of about 270,000 artifacts from the two dam locations [6][11][12].

In addition to that, the dam construction caused unauthorized deforestation in a permanent protection area and a decline in water quality and massive fish death after the opening of the dam, affecting villages that mostly had no other water and food supply [13a][13b]. A Kayabi leader described the impacts on the local community – an estimated 900 people in the immediate surroundings and 10,000 living downstream – as follows: “All this is a terrible sadness for our people. This region is sacred to us. Now, along with the land being flooded, they´ve dirtied our water. The fish have disappeared, too. People are getting sick with diarrhea. Everyone is worried about their health“ [13b]. In 2016, families near São Manoel Dam moreover became affected by an oil spill that was supposedly caused by EESM [13b].

These impacts have not come as a surprise but, on the contrary, had been repeatedly pointed out by environmental experts, indigenous groups, and civil society groups. Especially, the 2010-founded Fórum Teles Pires has emerged as an important public voice and network uniting over 30 social organizations, academics, and indigenous and riverine communities affected by infrastructural projects in the region. It regularly revealed the flaws of public agencies and the involved companies in (not-) complying with their legal requirements to compensate for damages and safeguard indigenous rights [1][4][5]. With the advancing of the project, Fórum Teles Pires moreover criticized EESM for a lack of transparency, for strategically using disinformation in public to silence the voices of affected communities, and for exerting pressure on them to renegotiate already agreed compensations [3][4].

As a consequence, central issues such as the non-consultation of indigenous groups, irregularities in the licensing, and compensations for environmental impacts became subject of court rulings that led to the temporary stop of the project for several times but became repeatedly overturned by public bodies who installed judges willing to apply a “safety suspension”, an instrument created during the military dictatorship to revert judicial decisions that cause damages to the public economy [4][11].

After the dam occupation in 2017, EESM moreover judicially attempted to ban indigenous people from demonstrating and entering the property, which also included the sacred site Dekoka’a. Framing the Munduruku as a “threat” to public order, the group was kept away from the site with the support of the National Force; in one protest in October 2017 even with the use of tear gas bombs [5][12][14][15].

In late 2017, after the Munduruku had been unsuccessfully calling for a meeting with officials, São Manoel Dam received its operating license from the president of Brazil’s environmental agency IBAMA - under indigenous protest. The decision ignored a previous assessment of the agency’s licensing department that questioned the environmental viability of the dam, noting the missing of requested data and failure in complying with the requirements of technical reports [3][4][5][11][16]. 

According to environmental researcher Philip Fearnside, this decision resulted from increasing political pressure on IBAMA and several changes in the environmental licensing process since 2002, leading to an easing of the procedure. For example, necessary requirements can now also be fulfilled in retrospect, but often only little is done to do so once the respective infrastructure is built [11]. An example in the case of São Manoel is the indigenous livelihood mitigation program, which was presented as a compensation measure – but in fact, designed without their participation, only poorly implemented and, in the eyes of the indigenous community, rather used as an instrument to undermine their rights [3][4][5].

In 2018, a number of civil society organizations publicly alerted about the imminent risk of conflict in the Teles Pires region and condemned the ongoing intimidation of opponents of São Manoel Dam: “Instead of agreeing to dialogue, the federal government dispatched the National Force to the building site to repress the indigenous mobilization carried out mainly by women and children” [5]. In the statement, they also criticized the ignoring of technical reports in the issuing of the dam’s operating license and the wrongful use of the safety suspension to circumvent socio-environmental legislation which “serves the interests of companies and their political allies, in detriment of the constitutional protection given to the environment, indigenous people and other traditional people” [5][15].

With the São Manoel and Teles Pires dams becoming a new reality, the mobilizing indigenous groups – most notably, the Munduruku - in recent years demanded compensations that would improve their social rights, for example, the creation of a regional indigenous university, access to health care, the preservation of sacred indigenous sites and the Munduruku culture, and the official demarcation of the Sawré Muyubu land as indigenous territory. They continued to demand the devolution of sacred funeral urns and other artifacts that have been removed during construction works – which in 2019 eventually resulted in the occupation of a natural history museum in the town of Alta Floresta [1][2][5].