As is known, Yamandú Orsi and the Frente Amplio promised in the electoral campaign that they would prioritize Casupá and avoid construction on the Río de la Plata for economic, technical and environmental reasons, something they achieved by renegotiating and carrying the new plant to Aguas Corrientes in addition to reactivating the construction of the dam.
A few months behind the original schedule, the work in Casupá recorded important progress this Thursday when the OSE board approved the specifications of the international tender that will be carried out.
The intention, according to President Pablo Ferreri, is to publish it next week.
The CCCC-YREC-Impacto consortia (made up of the companies CCCC Water Resources and Hidropower Construction Co., Ltd.; Yellow River Engineering Consulting Co., Ltd.; and Impacto Construcciones SA), Consorcio Casupá (Grinor-Sinohydro), Rovella CVC and Consorcio Constructor Presas Uruguay (Traxpalco-Berkes and Toniolo Busnello) that passed the prequalification will be the authorized to participate.
The work will be financed through a loan of US$ 130 million from CAF that has already been authorized.
Ferreri explained that the The idea is to award the work after receiving prior environmental authorization (AAP) from the Ministry of the Environment.. That procedure is still under study and the authorities estimate that it will be granted before the end of the year, so the works would begin in 2027.
Let the tender be awarded after receiving environmental authorization it will meanin turn, that the public hearing which will necessarily be done because this is what the law stipulates, will have OSE in the role of promoter of the worka significant difference with what happened with Arazati. In that instance, those who defended the project were the businessmen who promoted it.
The conduct of the hearing, which is expected complex because there are several groups of neighbors and producers –as well as the opposition– who are against the project It will be from the Ministry of the Environment, whose authorities have already expressed their support. Until now it has not been raised no scenario that suggests a possibility of rejection although there have been twists and turns regarding the water quality model and the contingencies due to the logging of native forests that are planned.
Ferreri also pointed out that OSE has already begun the expropriation process on the land where the workshop will be installed.
The felling of the native forest
The documents presented by the public company to obtain environmental authorization indicate that approximately 426 hectares of native forest. This surface represents the 20% of the total area that will be flooded by the reservoir.
The deforestation process will be carried out in a sectorized manner in two main stages. At the beginning of the work, smaller-scale logging will be carried out in the construction area of the diversion canal and cofferdams, while massive logging will be carried out in the final stage, immediately before filling the reservoir.
The loss of this forest is considered a significant environmental impact high intensitysince it has great ecosystem value by acting as a carbon dioxide filter, climate regulator, erosion controller and essential habitat for local fauna.
To mitigate and compensate for this loss, OSE proposed rescuing specimens, generating an environmental restoration project, implementing a revegetation plan with native species and operating a nursery (in cooperation with the Florida Municipality) to conserve the genetics of the area’s flora.
In turn, the Minister of the Environment, Edgardo Ortuño, has said that Casupá will be born with an associated protected area.
About 39 species of mammals, 32 of reptiles and 26 of amphibians live in the area. Vulnerable species stand out such as the long-nosed mouse, Darwin’s frog, and reptiles that live in the rocklands and grasslands such as the black-nosed lizard, the lizard, and the yara.
The presence of 111 species of birds was also recorded, which will suffer the loss of their feeding and nesting sites.
Doubts about water
The other issue that generates exchanges is the models that anticipate the quality of the reservoir water. The original model, presented by OSE during the Tabaré Vázquez government, focused on measure total phosphorus dynamicsconsidered the main limiting nutrient responsible for the uncontrolled growth of algae (eutrophication) in the Santa Lucía River basin.
As it is a reservoir not yet built, the engineers opted for a simplified mathematical model based on a mass balance, which assumes a uniform mixture of any compound that reaches the body of water. The results warned that the future lake will have a high probability of presenting a “eutrophic or close to this” state, according to the international indices of Carlson and the OECD. Despite this, the study concluded that the The quality of the outlet water would be between 5 and 10 times better than that currently recorded downstream, acting as a palliative to the pollution already existing in the river.
Despite these data, the model presented limitations, so Ambiente asked OSE for a more in-depth and comprehensive evaluation.
Environmental authorities required the use of more sophisticated toolssuggesting software such as the QUAL2 model, which allows the joint representation of the behavior of nutrients, temperature, dissolved oxygen and algal development. It was also required to use distributed hydrological models for the contributing basin, such as SWAT, in order to calculate diffuse pollution and evaluate the impact of different territorial management measures. All this new analysis must integrate the updated monitoring data collected during the period 2018-2025.
The Udelar Faculty of Engineering is intervening to improve the data.
The central objective of these demands is reduce the uncertainty associated with the project since Through precise simulations, we seek ensure that the dam fulfills its vital function without compromising the long-term health of the water ecosystem.
The work will have a storage volume of 118 million cubic meters which will be added to the 70 million from Paso Severino and the 10 million from Canelón Chico.
The basin area that will be intercepted reaches 685 square kilometers. The reservoir area will extend to 2,127 hectares and the expropriations will be 3,467 hectares.
