Lake Phewa is one of the largest lakes of Nepal. It is situated in Pokhara Valley in the western part of the country. The main inflows into this lake are two perennial spring-fed streams, Harpan Khola (Khola=stream) and Seti Khola. In addition, several temporary streams drain into the lake belongs to a warm monomictic type with thermal stratification. The lake water has very low electrical conductivity.

Lake Phewa is very young in geological terms as tree trunks are still standing in water down to 6 m depth. There are two versions about the formation of this lake. According to Hagen(1969), there was a "Paleo-Pokhara Lake" filling whole Pokhara basin and the existing lakes are the remails of the former huge lake. But Gurung (1970) and several other workers agree with the view that this lake was formed by damming of tributaries by sediments of Seti River.

Lake Phewa is one of the main sources of recreation, natural beauty, drinking water, hydroelecricity, fisheries and irrigation in Pokhara Valley(1,2,3).