Assessment of water quality trends in Loktak Lake, Manipur, India

Loktak Lake is the largest natural freshwater lake of Northeastern India, characteristic by floating islands, known as Phumdis. The lake supports rich biodiversity including some globally threatened species, hence declared as a Ramsar Site. The lake facilitates hydropower, irrigation and provides a livelihood to the local villagers in the form of fishing and agriculture. Loktak Lake is deteriorating in recent years due to rapid urbanization, increased settlement and other anthropogenic activities. A study was, therefore, undertaken to assess the water quality and its trends for this important lake. The water quality of Loktak Lake was assessed in monthly intervals for a period of 3 years, using multiple water quality indices. Temporal distribution functions of the individual water quality parameters and indices were developed to assess the water quality trend of the lake. Overall water quality of this lake was found to be good throughout the year with slight deterioration during winter. However, the water of this lake was a little turbid and contained significant organic load.