Loktak Lake - Loktak Multipurpose Project

Loktak Multipurpose Project

The Loktak Hydropower Project on the Manipur River or Imphal River, with the Loktak Lake forming the head waters to provide regulated storage for power generation, was built in 1983 as a multipurpose project with power generation of 105 MW (3x35 MW) for power supply to Manipur, Nagaland, Assam, Mizoram, Arunachal Pradesh, Meghalaya and Tripura, and lift irrigation to an area of 23,000 ha (57,000 acres) in the Manipur valley. The main components of the project, as built, are, a) the Ithai barrage, across the Manipur river of 10.7 m (35.1 ft) height and 58.8 m (192.9 ft) length with three spillway bays, b) water conductor system for trans-basin diversion comprising an open channel of 2.323 km (1.443 mi) length, a cut and cover section of 1.077 km (0.669 mi) length (bed width 18 m (59 ft), followed by a Head Race Tunnel of 3.81 m (12.5 ft) diameter (horseshoe type) and 6.62 km (4.11 mi) long to carry a discharge of 58.8 m3/s (2,080 cu ft/s) (42 m3/s (1,500 cu ft/s)) for power generation and 16.8 m3/s (590 cu ft/s) for irrigation), c) a surge shaft, d) penstocks and e) a surface powerhouse and a tailrace channel on the right bank of the narrow Leimatak River with three units of 35 MW capacity each generating an annual energy of 448 GW·h (1.613 PJ). The downstream Loktak Power Project in cascade to utilize the regulated releases from the upper project for further power generation of 90 MW is proposed to be taken up for joint implementation by NHPC and the Government of Manipur. The project has invited severe criticism since the water level in the lake at the Ithai barrage is maintained throughout the year at FRL 786.5 m (2,580 ft) from considerations of power generation from the well planned water conductor system. The problem in the lake is, however, diverse; economic activities in and around the lake, and encroachments by 50,400 fishermen for extensive fishing activity are also cited to be some of the reasons. Other reasons for the distress situation in the lake are a) jhum (shifting) cultivation, b) extensive deforestation and unscientific land use practices in the catchment areas which bring large amount of silt into the lake and c) undefined ownership of the lake where the stakeholders are the districts of Imphal west district, Bishnupur and Thoubal causing lack of integrated approach to the lakes potential for providing benefits.