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scoping exercise.18 In this case, the screening was based on the initial environmental classification19 of a sample of Bank-financed electricity sector projects completed over four years ago. The objective of the evaluation is to develop an ex post environmental evaluation methodology. Accordingly, the selection focused on projects with ample ex ante environmental data to permit an in-depth study for this exercise. Following the screening, a review was made of existing bibliography20 and of the information contained in numerous ex ante environmental analysis documents (EIA and the Bank’s validation reports) and environmental monitoring. The purpose was to select the most relevant environmental aspects21 to determine the ex post environmental impact of some of the project’s mitigation measures for which there was sufficient data (scoping). 2.13
Only seven out of 19 selected environmental aspects monitored by EPM were deemed relevant by the scoping exercise as the environmental impacts generated were significant for purposes of the ex post environmental evaluation. Subsequently, two of the seven aspects were rejected for lack of sufficient quality data.22 Therefore, the trends for five environmental aspects were considered: a. Water quality, including water upstream, in the reservoir and exiting the turbine, the issue expected to yield the most significant impacts due to the creation of a eutrophic reservoir with water of moderate quality. b. Invasive aquatic plants, given their potential to provide a habitat for tropical disease vectors, diminish the quality of the environment through decomposition, and silting of the reservoir. c. Land plants, considering the forest coverage lost as a result of formation of the reservoir and other project-related works.
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The EIA Follow-up methodologies (including monitoring activities, audit, evaluation and environmental management systems) advocate first determining the need for an ex post environmental evaluation for a specific project (screening) and, if necessary, prioritizing the issues to be studied in detail (scoping). This preliminary analysis ensures that ex post evaluations are conducted for projects with significant adverse environmental issues. The classification is prepared by the ministries for the environment as part of the Environmental Impact Assessment, and validated by the Bank’s Committee on Environment and Social Impact (CESI) to ensure the environmental viability of loans to be approved. In this case, the projects with the highest environmental impact classification were considered. Dee (1973), Conesa (1997), Ramírez and Viña (1998), CEPIS (2001), Thomaz et al (2004). “Relevant” environmental aspects are those subject to significant environmental impacts. Internationally accepted EIA bibliography suggests that significant impacts include those that impact health and public safety, areas and ecosystems considered sensitive on the basis of their natural or cultural interest, or that generate an effect regulated by environmental legislation (IDB, 2001). The two rejected aspects were Erosion (vulnerability to erosion of the basin and the shores of the reservoir, as principal contributors to sedimentation) and Public Health (increased incidence of tropical vector-transmitted diseases in the proximity of the dam). Annexes 2 and 3, respectively, present a summary of the data collected on these environmental aspects.