Rara Lake, also known as Mahendra Tal (Lake), is the biggest and deepest freshwater lake in Nepal in Mugu District of Nepal. It lies in the territory of Rara National Park, the smallest national park of Nepal. It is one of the best trekking deastinations of Nepal. Rara Lake was declared a Ramsar site, covering 1,583 ha (6.11 sq mi) including the surrounding wetland.
Rara Lake lies at an altitude of 2,990 m (9,810 ft) above sea level. It has a water surface of 10.8 km2 (4.2 sq mi), a maximum depth of 167 m (548 ft), is 5.1 km (3.2 mi) long and 2.7 km (1.7 mi) wide. It drains into the Mugu Karnali River via the Nijar River. Its water quality is characterized by high pH, conductivity and total hardness.
winter is cold whereas summer is quite pleasant. April to June is warm. Monsoon season is short, which occurs in between the months of July to October. The temperatures go low below the freezing point and heavy snowfall occur, blocking the way to the lake between the months of December to March. The average rainfall during the ten-year period 1994–2003 was 800 mm. The surface temperature of the lake was found to be 7.5 °C to 7.6 °C and was visible below 14 m to 15 m.
The best visiting time to the lake is September/October and April to May.
Being surrounded by Rara National Park, Rara Lake has unique floral and faunal importance with rare and vulnerable species. The park was established in 1976 to preserve the beauty of the lake and protect it from sedimentation and adverse human activities. The Park flora consists of 1074 species, of which 16 are endemic to Nepal; the fauna includes 51 species of mammals and 214 species of birds.
The lake isthe habitat for three endemic fish species (Schizothorax macrophthalmus, S. nepalensis and S. raraensis) and one endemic frog, Rara Lake frog (Nanorana rarica). Winter visitor water birds such as gadwall (Anas strepera), mallard (Anas platyrhynchos), northern shoveler (Anas clypeata), common teal (Anas crecca), tufted duck (Aythya fuligula), common golden eye (Bucephala clangula), common merganser (Mergus merganser), common coot (Fulica atra), and solitary snipe (Gallinago solitaria) reside and rest at this lake.
Many people are engaged in agriculture, which is the main occupation of the people living around the area. People also rear goats and extract medicinal herbs and sell them for their living. Thakur society is dominant in the community. Thakur Baba’s Temple is situated in the southeast corner of the lake. Local people believe that the god Thakur shot an arrow to open the passage of the lake reducing the damage caused by flooding.
Due to over-grazing and defecation, the national park conservation officers are facing a challenge to preserve the lake. Local people are found cutting timber wood and fuel wood, which is a problem for conservation of Rara. Also during festivals visitors and local people produce a lot of wastage causing water pollution.