
The Ganges river dolphin historically ranged from Ganges-Brahmaputra-Megna (GBM) and Karnaphuli-Sangu (KS) river systems, from the deltas upstream to where rocky barriers, shallow water, fast currents, dams, or barrages (low, gated, diversion dams) prevent upstream movement in Nepal, India and Bangladesh but now only remains in highly fragmented populations across Ganges and Brahamaputra river system. The species is extinct from most of its early distribution ranges.