Downstream Consequences of Large Dam project: Environmental Degradation and Social Vulnerability in the downstream of Mapithel Dam, Thoubal River, Manipur

Abstract

Large dam projects in India are commonly evaluated through upstream displacement and infrastructural benefits, while the downstream impacts remain poorly documented. This study examines the environmental, livelihood and health consequences experienced by downstream communities of the Mapithel Dam on the Thoubal River, Manipur. Primary data were collected from 200 respondents across 20 downstream villages using structured field surveys. The findings indicate a marked deterioration in river water quality following dam construction, characterised by increased turbidity, stagnation, odour and reduced natural flow. These changes have significantly altered patterns of river water utilization with sharp declines in drinking, cooking, and bathing, alongside reduced agricultural productivity. Many households reported moderate to severe declines in crop yield. Health impacts, including skin infections and sanitation related illnesses particularly among women were reported. Despite physical accessibility to the river, declining water quality has fundamentally reshaped everyday practices and livelihood security. The study highlights a critical governance gap in dam impact assessments, where downstream effects are excluded from social and environmental monitoring. By highlighting lived experiences and empirical evidence, this paper argues for basin wide impact assessments and inclusive water governance that recognises downstream communities as integral stakeholders in sustainable development planning.