Social, economic and environmental trade-offs of hydropower mega-dams in the Eastern Himalaya: Community perceptions from the Teesta River basin, Sikkim

Mega-dams are typically promoted for hydropower generation, flood control, and regional development; however, they frequently impose significant social, economic, and environmental costs on surrounding populations. This study examines the externalities of a Mega-Dam Project on the Teesta River basin in Sikkim, with particular focus on public perceptions across diverse socio-demographic groups. Using a structured questionnaire survey of 123 respondents, data were analyzed through SPSS (v.26) for normality, correlation, mean rank, and chi-square, with reliability confirmed by Cronbach’s Alpha (0.851), indicating high internal consistency. Results revealed that 47% of respondents perceived negative social impacts, especially displacement and the disruption of community networks. Environmental concerns were more pronounced, with 64% identifying biodiversity loss, ecosystem degradation, and water pollution as the most serious issues. Younger respondents showed heightened concern for environmental degradation, while older participants emphasized economic benefits. Overall, the findings underscore inequities in the distribution of costs and benefits, reflecting limited community consultation and inadequate safeguards. The study highlights the urgent need for participatory decision-making, inclusive policies, transparent benefit-sharing, and credible environmental protection measures to ensure that hydropower development in the Teesta basin follows a more equitable, sustainable, and community-centered trajectory.