Loktak Lake

Loktak Lake is the largest freshwater lake in North- Eastern India, also called the only Floating lake in the world due to the floating phumdis (heterogeneous mass of vegetation, soil, and organic matters at various stages of decomposition) on it. It is located near Moirang in Manipur state, India. Its catchment area is 980 km2 out of which 430 km2 is under paddy cultivation, 150 km2 under habitation and 400 km2 under forest cover. The area of the lake has shrunk from 491 km2 in 1971 to 236.21 km2 as of now.

This ancient lake plays an important role in the economy of Manipur. It is considered to be the lifeline for the people of Manipur due to its importance in their socio-economic and cultural life, besides influencing the climate of the State. It serves as a source of water for hydropower generation, irrigation and drinking water supply. The lake is also a source of livelihood for the rural fisherman who lives in the surrounding areas and on phumdis. The traditional fishermen stay on these phumdis by constructing khangpok (huts). Considering the ecological status and its biodiversity values, the lake was initially designated as a wetland of international importance under the Ramsar Convention on March 23 1990.

The Loktak lake and its precincts have faced serious problems due to loss of vegetal cover in the catchment area and construction of Ithai barrage at the outlet of the lake for multipurpose development of water resources. The degradation of the catchment area has led to the problems of siltation. The sediments deposit at the mouth of the rivers contributes to shallowing of the lake bottom. As the lake become shallower the level of the water also rises. Thousands of hectares of cultivable lands and grazing fields are submerged into the water. The domestic sewage from Imphal city carried by Nambul River is discharged into the lake affecting its water quality, thus leading to eutrophication. The size of the natural habitat of the brow antlered deer (sangai), which forms a part of the catchment area, has shrunk from its earlier 40 sq km to only 6 sq km now. Thus this species is under the verge of extinction.

Due to construction of the Ithahi barrage in 1979, the water level in the wetland increased and the movement of water in and out of the waterbody got reduced. This led to increase of siltation in the lake. The construction of the barrage also inundated the area and more people migrated to the phumdis for shelter and took up fishing for their livelihood. The phumdis is one of the major threats to the lake. The growth of phumdis blocks the sunlight falling on the lake and thus affects the fishes in the wetlands. Remote sensing studies conducted jointly by the Manipur Remote Sensing Application Centre and the Space Application Centre, Ahmedabad (1999) shows that the area under phumdi has increased from 10,499 ha. in 1990 to 13,506 ha. in 1994. Consequently, the water mass has reduced from 15,441 ha. in 1990 to 7,875 ha. in 1995. The live of a phumdis is up to 20 years, after that it sinks into the lake causing all the possible environmental degradation to the lake.

During the 80s the Government of Manipur had introduced many species of fishes, amphibians, insects and plants into the Loktak Lake without any concerns about the future consequences of the introduction of new and alien species. These have caused many perturbations to the lake ecosystem and indigenous species of fishes, plants and animals are rarely seen now.

State Government of Manipur constituted Loktak Development Authority (LDA) in 1986 to check deterioration of the lake and to bring improvement in the areas of power generation, fisheries, tourism and siltation control. A project on Sustainable Development and Water Resources Management of Loktak Lake (SDWRML), jointly formulated by Wetlands International South Asia (WISA) and LDA was initiated in 1997 to address the root cause problems and develop strategies for sustainable management of the lake, with financial support provided by India-Canada Environmental Facility. Loktak Development Authority, and India-Canada Environment Facility have brought out a publication 'Atlas of Loktak lake' in 2004 that presents information on ecological, hydrological and socio-economic aspects of this Wetland of International Importance in India.