is estimated to be 3500 years old. The lake is situated amidst pristine forest at an altitude of near Tsozo village. The lake drains a catchment area of the Ramam watershed (Ramam mountain gives its name to the valley) and has a drainage area of (including area of bog of . The periphery of lake has the shape of a foot. The surface water spread area of the lake is . The depth of water in the lake varies from with an average depth of . It is also inferred from a visual observation of the lake that it has undergone changes in its size due to encroachment due to peripheral vegetation and eutrophication, and its original size could have been three times of its present size. The lake's water spread, which was in 1963 reduced to in 1997 and consequently the peatland (bog) increased from . Inflow into the lake is through two perennial and five non perennial streams, while the outflow is from one outlet. In addition, during the monsoon season two streams are also diverted temporarily into the lake to supplement its storage capacity. The geological setting in the lake and its surrounding hills consist of granite gneiss, schist and phyllites. The lake is enveloped in a dense forest cover of temperate vegetation and bamboo. 72 households and 440 people live in villages around the lake periphery. The Lepchas are the main ethnic group of the place. Traditional agriculture is the main livelihood and recently some households have become involved in tourism. Pelling–Yuksom road leads to the lake, which is surrounded by densely forested hills. There is also a monastery above the lake. Climate The climate of the lake region is monsoonal. The maximum and minimum temperatures recorded are and . Flora and fauna Vegetation The lake is surrounded by a broad-leaved mixed temperate forest. However, the vegetation in the lake comprises Macrophytes, Phytoplankton and Zooplankton. The Phytoplankton species are a composition of different families namely, Chlorophyceae (18) which is the foremost group, Chrysophyceae (15), Cyanophyceae (11), and one species each of Charophyceae, Euglenophyceae, Dinophyceae and Cryptophyceae. The Zooplanktons recorded are: 7 rotifers, 5 protozoans, 2 each of copepods and cladocerans, and 1 each of ostracods and isopods. Aquatic fauna The fish species recorded in the lake are: Cyprinus carpio, Danio aequipinnatus, Garra sp., Schistura sp. and Schziothorax sp. Avifauna The avifauna recorded in the lake, particularly