Chilika Lake, situated on the east-coast of India, is an estuarine lagoon, shallow throughout its spread of 1,16,500 ha. It is the largest brackish water wetland in India. The water spread area of Chilika varies between 1165 to 906 sq.km during the monsoon and summer respectively. A 32 km long, narrow, outer channel connects the main lagoon to the Bay of Bengal, near the village Motto. The mouth connecting the channel to the sea is close to the north eastern end of the lagoon. Chilika lake is subject to minor tidal fluctuations. The major tributary rivers are Daya and Bhargavi. It is the largest wintering ground for migratory waterfowl in India. According to historical evidence, Chilika Lake was part of the Bay of Bengal about 6,000 years ago. Merchant ships used to travel from Chilika to South East Asia. Over a period of time, a sand spit barrier formed due to the littoral drift of the sea, as well as silt deposits carried by adjoining rivers into the wetland, separating it from the Bay of Bengal. Several islands are located in the lagoon covering an area of 22,300 ha.
In 1992, the Government of Odisha, concerned by the degradation of the lake's ecosystem and cognizant of significant numbers of people who were dependent upon the lake's resources, set up the Chilika Development Authority (CDA). The CDA was set up for restoration and overall development of the lake under the Indian Societies Registration Act as a parastatal body under the administrative jurisdiction of the Forest and Environment Department, with the following charter:
"Nalbana Island is the core area of Chilika Lake. Nalbana means a weed covered island In the Oriya language. Nalbana was notified as Bird Sanctuary in 1987 under the Wildlife Protection Act, 1972. Nalaban remains the highest migratory bird congregated island in the lagoon. Next to Nalaban (Sanctuary, protected area, mited entry for tourists), second highest congregation of migratory birds takes place at Mangalajodi, the area on the northern bank of Chilika, which is about 70 km from Bhubaneswar the state capital of Odisha. Chilika is a hot spot as eco tourist destination. Apart from Mangalajodi and Nalaban (limited entry for tourists), other places of attraction are Rambha, Barkul, Rajhans (also limited entry for tourists), Kalijai Island, etc.
There are a number of small Islands dotted across Chilika. These small Islands are very attractive. Boat ride to these Islands is a mesmerizing moment."