Attention to impact pathways in EISs of large dam projects

The importance of addressing cumulative environmental impacts in Environmental Impact Statements (EISs) of large development projects is increasingly underlined. However, cumulative impacts are generated through complex impact pathways, involving multiple root causes and lower and higher order effects, interlinked by cause–effect relationships. Consideration to potential impact pathways may thus be difficult without appropriate analytical methods, expertise, and supportive Environmental Impact Assessment guidelines and terms-of-references (TOR). This paper presents the results of an analysis of six EISs prepared for large dam projects between 1994 and 2001. The objective was to analyze if, how, and to what extent potential impact pathways involved in the generation of dam-related cumulative impacts have been addressed in the analyzed material. For this purpose, a theoretical framework was developed, which identifies four key root causes, their potential effects, and associated cause–effect relationships. The analysis revealed various shortcomings. Important imbalances were found in the degree of attention given to effects of different categories. Lower order effects received greater attention than higher order, and the potential effects of reservoir filling were more extensively attended to than those of flow blockage, storage, and regulation. Most importantly, little effort was made to carefully explain the potential impact pathways involved; root causes were often referred to in general terms only, and potential pathways leading up to an anticipated higher order effect or following upon an expected lower order effect were often inadequately addressed or ignored. Probable reasons for the discovered shortcomings are discussed and recommendations are presented for improving the World Bank EIA guidelines for large dam projects.