This study investigates the hydrological alteration of the Ganges River in the context of three distinct periods: pre-Farakka (1960–1975), post-Farakka (1976–2019), and the post-Ganges Water Sharing Treaty (GWT) period (1997–2019) using Indicators of Hydrologic Alteration (IHA) software. The Ganges River, shared by India, China, Nepal, and Bangladesh, is vital for the socio-economic and environmental well-being of the region. The Barrage at Farakka that was constructed in 1975 altered the natural flow of the Ganges, impacting downstream riparian country Bangladesh. Despite a water sharing agreement in 1977 and subsequent treaties, unilateral withdrawals by India persisted, leading to major impact to the downstream riparian as well as river health. With the historical discharge data of the Hardinge Bridge point the IHA software was used to assess the hydrologic alteration for the Ganges River in Bangladesh. Results show that some improvement has been achieved in post treaty period regarding river hydrology. The Hydrologic Alteration (HA) in pre-treaty period was 59 whereas in post-treaty period the HA is 55. However, Environmental flow parameters are suffering significantly in the post Farakka period. The findings contribute valuable insights for policymakers seeking to balance water sharing, economic needs, and ecological sustainability in the Ganges basin.