The combined impacts of numerous small hydroelectric dams in one river basin can be at least as harmful as one large dam, warn experts, environmental activists and indigenous groups, who face a flood of new projects along the rivers of the western Brazilian state of Mato Grosso.
The combined impacts of numerous small hydroelectric dams in one river
basin can be at least as harmful as one large dam, warn experts,
environmental activists and indigenous groups, who face a flood of new
projects along the rivers of the western Brazilian state of Mato
Hydraulic energy from small dams "is interesting because of its low environmental costs, but everything has its limits," says AndrÃ© Villas-Boas in reference to their proliferation along the tributaries of the XingÃº River, in the Amazon.
At least six small dams are concentrated on the rivers in northeast Mato Grosso, points out Villas-Boas, coordinator of the XingÃº Programme of the non-governmental Socio-Environmental Institute (ISA). Two have already been built and a third has been given the green light by the energy and environmental authorities for the Culuene River alone, the main tributary of the XingÃº.
Such projects should not be authorised without an integral assessment of the river basin in its environmental and social aspects, for a planned exploitation of the water resource as a whole, and limits on the number of hydroelectric dams, according to Villas-Boas, who notes that more than half the area of the XingÃº is indigenous territory.
The dams are located around the XingÃº Indigenous Park, a symbol of Brazil's indigenous policy that is home to some 5,000 people from 14 different ethnic groups.
Often included among "clean" sources of energy, small hydroelectric dams have become an attractive business for the "soft legislation" under fiscal and financial control and incentives, without duly considering that "they seriously alter biological dynamics" if there are many in one watershed, says Villas-Boas.
As a result, there are 240 small hydroelectric dams planned in Brazil, according to the National Electric Energy Agency (ANEEL). The 81 dams already under construction will produce 1,342 megawatts, or 17.29 percent of the total power supplies.
An example of a more unsustainable panorama is the Juruena River, according to Raul do Valle, an attorney who coordinates ISA's political and legal actions. In the Juruena basin, in northwest Mato Grosso, 83 hydroelectric dam plans have been registered. ANEEL suspended 30 projects in early July and decided to pursue integrated environmental assessments for them.
There have been several cases where indigenous people have taken government officials or construction company employees hostage, in a bid to bring the work on dams on the Juruena and the Culuene rivers to a halt. In other efforts, lawyers have tried to do so through legal channels, obtaining temporary suspensions of construction permits. There are many cases where a final decision is still pending.
"We predict that there will be fewer fish" as a result of the energy projects on local rivers, begun around 10 years ago, because the dams "block the fish from swimming upriver to breed," said Paulo KamaiurÃ¡, who has taken as his surname the name of his tribe, who live in the XingÃº Park.
The affected rivers, which are already polluted by agro-chemical runoff, flow towards the Park where they form the XingÃº River, and as a result "the problems will be aggravated," said KamaiurÃ¡, adding that it is essential to mobilise indigenous communities to raise awareness about the threats.
Because of their presumed limited ecological impact, environmental permits for small hydroelectric dams are granted by state, not federal, agencies. And the state bodies are more vulnerable to local economic pressures, says Valle.
But the permits must be issued by the national Brazilian Environmental Institute when the projects affect Indians, he explains. In the case of northern Mato Grosso, it is a matter of survival of native peoples, who rely on fish for subsistence, he adds.
That is the main argument against the dams in the legal cases that are still pending. The counter-argument set forth by the construction companies and state authorities is that the indigenous groups do not suffer direct impacts, given that their lands are dozens of kilometres away from the dams.
But Valle stresses that there is no need for local production of electricity, given that the nearby cities are connected to the power grid, so there is no justification for this "destructive activity" in benefit of private enterprise. But the slow pace of justice favours the "consummated fact," he admits, noting that it is nearly impossible to stop dam operations after they have been built.
The dams reduce the quantity of fish in the rivers because they alter currents and nutrition, in addition to eliminating migratory species. Attempts to reestablish reproduction have not been successful, according to Juarez Pezzuti, a biologist who conducted a study of the effects of Paranatinga II, a small hydroelectric dam operating on the Culuene.
The impacts could be mitigated if there are prior studies and planning, and with the participation of local communities, who are the ones left facing the threats and often do not even benefit from the energy generated in their backyards, says Pezzuti, professor of advanced environmental research at the Federal University of ParÃ¡.
In another area of Brazil, in Santo Amaro da Imperatriz, a town in the southern state of Santa Catarina, a project involving six small dams triggered reactions that led the local council to ban hydroelectric dams in the district, with only one dissenting vote.
The ban is unconstitutional, admits Environment Secretary Joao Renato Duarte. But "99 percent of the population is against" the dams and the project will only be approved if it can be verified that they will not harm the hot springs, waterfalls and rapids that attract tourism and provide recreational and cultural activities for local citizens, he said.
The dams are to be built using the latest European technologies, channeling only a portion of the river flow through tunnels, without affecting the landscape or river rafting, which is what feeds local tourism, says engineer Helio Machado, head of the project. The people opposed to the endeavour are talking about ridiculous threats like flooding or the drying up of the CubatÃ£o River, because they don't know the details, Machado says.
"It doesn't make sense to destroy the natural heritage" of the city in order to generate just 14 megawatts, retorts Eliazar Garbelotto, who runs a rafting business on the CubatÃ£o.
The tourism sector is radically opposed to the small hydroelectric dams. There are five rafting businesses that bring in about 10,000 tourists a year, and employ just 50 people, but feed other tourist activities as well as providing environmental education, Garbelotto says.