While the negative environmental impacts of dams are well-documented, their role in freshwater distribution and clean energy production is increasingly vital under climate change. Traditional analyses using historical streamflow data to assess dam-induced changes in downstream flow regimes face limitations due to the scarcity of long-term pre-dam records and spatial constraints. This study adopts an alternative approach by using in-channel vegetation cover, derived from remote sensing data, as a proxy for detecting changes in streamflow regimes. The underlying principle is that frequently inundated channel areas remain unvegetated and sandy, while less inundated areas promote vegetation growth and soil stabilization. The study focuses on major east-flowing rivers in peninsular India—the Godavari, Mahanadi, Krishna, Brahmani, Damodar, Kansabati, Baitarani and Subarnarekha—which have been hotspots of dam building activity over the past 70 years. It evaluates temporal changes in in-channel vegetation cover from 1987 to 2022. Results reveal three key insights: (a) a regional increase in vegetation cover at the expense of bare soil suggests a widespread downstream impact of dams; (b) the influence of dams on the downstream annual hydrograph diminishes with increasing distance from the dam and (c) within individual river reaches, the impact of dams is uneven, influenced not only by distance from the dam but also by local channel slope. These findings highlight the effectiveness of remote sensing-based vegetation analysis as a practical and spatially extensive method for assessing hydrological alterations caused by dams.