The Ithai Barrage impounds the Manipur River just below the confluence of the Imphal River and the Tuitha River south of Loktak Lake, and is part of the Loktak Hydroelectric project that supplies hydropower to the seven Northeast states. Over time, the dam has affected the hydrology of the lake and caused harm to the ecology and economy of the region. The Manipur government is now urging the Centre to consider decommissioning the barrage. This brief assesses the present condition of the Loktak lake and the hydroelectricity project to arrive at a policy recommendation on whether or not the Ithai Barrage should be shut down. In August 2017, the N. Biren Singh government in Manipur wrote to the union government seeking a review of the Loktak Hydropower project and removal of the Ithai Barrage. Nothing like this has ever been done in Indiathe country does not have a history of systematic dam decommissioning due to ecological concerns. Obstruction of traditional fishing The construction of the Ithai Barrage has impacted the natural hydrological regime and obstructed the migratory routes of fish through the Manipur River. As a result, there has been a substantial decline in the population of riverine fish like Pengba, Khabak, and Shareng. Ataphum and phumdi proliferation The people living around the lake were dependent on it for fishing. With the loss of their residential and agricultural lands and a decline in the fish population, they have become more dependent on the ataphums (floating fishing ponds). Traditionally, ataphum fishing was a monsoon activity. But with the construction of the Ithai Barrage and the continuous high water level, ataphum is now carried out through the year, resulting in a proliferation of ataphum and phumdis. However, the presence of many ataphums obstructs the movement and circulation of the water and sediments in the lake. An estimated 25 percent of the lake’s water-holding capacity has been lost due to the annual deposit of 336,325 tonnes of silt. The enhanced sedimentation is partially due to the obstructed flow pattern inside the lake caused by the proliferation of phumdis and ataphums. The lake’s navigational benefits have also decreased due to the ataphum’s interference. Some fisherfolks have started using non-traditional practicessuch as using insecticidesthat have had an extremely detrimental impact on the water quality and aquatic biodiversity. Such hazardous chemicals not only poison but also increase the nitrogen levels in the water, leading to an unhealthy burst of the phumdis. The phumdis and other suspended vegetation eventually meet effluents brought to the lake by the Imphal River from Imphal’s sewages. This causes a horizontal proliferation of surface vegetation over the lake, obstructing sunlight and causing harmful vegetation blooms that could choke the lake.