Many natural lakes are found in the plains of Bihar. In the northern part of Bihar, the river flow becomes very slow due to the low slope in the Gangetic plain. Due to this the sediment brought by the river along with it is deposited at the same place, as a result of this, the formation of eroded shape starts. Gokhur Lake has been formed by rivers like Ganga, Budhi Gandak, Kosi, Mahananda etc.
The main lakes found in the northern Bihar plain are Kanwar Lake, Kusheshwar Lake, Ghogha Lake (Ghogha Chap), Simri Bakhtiyarpur Jhol, Udaipur Jhol, etc. The lake-like submerged area in Bihar is also known by names like Tal, Chaur, Mana, etc. These submerged areas are called wetlands .
Following are the major lakes of Bihar –
Kanwar Lake is situated in Manjhol village of Begusarai. The area of this lake is 16 square kilometers. It is the largest Gokhur lake in Asia, which was formed by the digression of the Gandak river. The main vegetation found in this lake is the following, in which Hydra laricillae, Potomogentan, Welsneria, Leplerales, Niphasa, Mympholodes, Sarpus Vetlveria, etc. are prominent. The lake is visited by migratory birds from the Siberian region during winter (November-January). According to Salim Ali, a leading ornithologist, about 60 species of birds come from Central Asia to live here in winter and basically, about 106 species of birds reside here.
Kusheshwar Sthan Lake is located in Kusheshwar of Darbhanga. Whose area varies from 20 square kilometers to 100 square kilometers. Due to the excess water during the rainy season, the lake expands immensely. Water collects in this lake from rivers like Kamala, Kareh, etc. This lake is a major center of fish production. Here also the migratory birds' Pelican Dalmatia and Siberian Cranes migrate during the winter season. In 1972, this lake has been declared as a bird sanctuary.
Ghogha lake is situated in the Manihari area of the Katihar district. Its area is about 5 square kilometers. Many small lakes are situated around this lake.
Simri-Bakhtiarpur Lake is located in the Saharsa district of Bihar. Which is formed by the union of many small lakes. Lakes like Jamuniya, Sardia, Kumibi, Gobra, etc. are prominent in this.
Bird Banding Station has been established for research work near Kanwar Jheel lake.