Kolleru Lake is one of the largest freshwater lakes in India located in state of Andhra Pradesh 20 kilometers away from the city of Eluru. Kolleru is located between Krishna and Godavari delta. Kolleru spans into two districts - Krishna and West Godavari. The lake serves as a natural flood-balancing reservoir for these two rivers. The lake is fed directly by water from the seasonal Budameru and Tammileru streams, and is connected to the Krishna and Godavari systems by over 68 in-flowing drains and channels.this lake is a major tourist attraction. Many birds migrate here in winter, such as Siberian crane, ibis, and painted storks. The lake was an important habitat for an estimated 20 million resident and migratory birds, including the grey or spot-billed pelican (Pelecanus philippensis). The lake was declared as a wildlife sanctuary in November 1999 under India's Wildlife Protection Act of 1972, and designated a wetland of international importance in November 2002 under the international Ramsar Convention. The wildlife sanctuary covers an area of 308 km2.
Thousands of fish tanks were dug up effectively converting the lake into a mere drain. This had great impact in terms of pollution, leading to difficulty in getting drinking water for the local people. This is in addition to the loss of ecological diversity and intrusion of sea water into the land masses and its fallout in terms of adverse influence on the rainfall pattern in this region. This imbalance has an adverse effect on the thousands of acres of crop in the upper reaches of sanctuary in view of stoppages water flow into the sea because of obstruction by bunds of the fish tanks that appeared illegally.
Satellite images taken on February 9, 2001 by the Indian remote sensing satellite found that approximately 42% of the 245 km2 lake was occupied by aquaculture, while agriculture had encroached another 8.5%. The area under aquaculture consisted of 1050 fish ponds within the lake and 38 dried-up fish ponds, which together covered an area of 103 km2. The agricultural encroachments were mostly rice paddies. Surprisingly no clear water could be found in the satellite image. The rest of the lake is being diminished by water diversions or was infested with weeds like elephant grass and water hyacinth. Rich in flora and fauna, it attracts migratory birds from northern Asia and Eastern Europe between the months of October and March. During this season, the lake is visited by an estimated two million birds. The resident birds include grey pelicans, Asian open-billed storks (Anastomus oscitans), painted storks (Mycteria leucocephala), glossy ibises, white ibises, teals, pintails and shovellers. The migratory birds include red-crested pochards, blackwinged stilts, avocets, common red shanks, wigeons, gadwalls and cormorants, garganeys, herons and flamingos.
Kolleru lake contains numerous fertile islets called lanka's,many of the small ones are submerged during floods. The origin of unusual depression which forms the bed of the lake is unknown, but it was possibly the results of an earthquake. Therefore, many ancient villages are precepted in the bed of the lake as a result of floods and earthquake.
Two copper plates of the early Pallava dynasty have been found in the lake, tracing its history to Langula Narasimha Deva (Langulya Gajapathi Raju) an Ganga Vanshi Odisha king, (Oddiya/Odia raju)Vaddiya Rajulu/Vaddi. According to legend, the Gajapathi fort was located at Kolleti Kota on one of the eastern islands of the lake. The enemy general "muhammadan" probably a Bahamany general encamped at "Chiguru kota" located on the shores. In some ways, the lake protected the Odia forces. The enemy finally tried to excavate a channel, the modern-day Upputeru, so that the water of the lake would empty into the sea and the level would fall so that they could attack the Gajapathi fort. The royal Odia army general sacrificed his own daughter to propitiate Gods and ensure his success against Muhammadan and her name was "Perantala Kanama". Therefore, the channel was called Perantala Kanama.
The Suryavanshi Gajapatis of Odisha, on the height of their power in the 15th century, ruled over a kingdom extending from the Ganges river in the north to the Kaveri in the south under Gajapati Kapilendra Deva. But by the early 16th century, the Gajapatis lost great portions of their southern dominion to Vijayanagar and Golconda.The Gajapatis were a medieval Hindu Suryavamsi dynasty of Kalinga- Utkal Odisha who ruled large parts of Andhra Pradesh, West Bengal, Bihar and Madhya Pradesh. During the glorious reign of Kapilendra deva, the first Suryavamsi Gajapati emperor, the boundary of the Kalinga empire (Ancient Odisha) stretched from river Ganges in North to Kaveri in South and from Amarkantak in West to Bay of Bengal(Kalinga Sagara) in east. This lake has a disaster story regarding a quotation many people use it when they lost everything "Na kompa kolleru aiyindi " it meant that back in '50s many of the people of Telaprolu village head family's has invested and boughtlands near kolleru lake due to expansion of lake they lost all their properties.
The sanctuary has the following watch towers for sighting the birds.
Atapaka: 1.5 km from Kaikaluru to see varieties of waterfowl. Murthyraju tank 8 km from Nidamarru East Chodavaram: 53 km from Eluru where openbill storks nest in colonies from July to December.
Purple heron (Ardea purpurea) in Kolleru
The sanctuary is approachable from all four sides of the lake by road, directly to the following places.
Atapaka – 2.5 km from Kaikaluru town
Bhujabalapatnam - 6 km from Kaikaluru town
Kovvada Lanka—7 km from Kaikaluru town *Murthiraju Tanks – 8 km from Nidamarru
Gudivakalanka – 3 km from Gudivakalanka or 15 km from Eluru, The nearest city by road or rail.
Prathikola Lanaka or 19 km from Eluru. The nearest city is Eluru, which is 35 km by road.
Accommodation: Hotels in Eluru, Kaikaluru, Akividu, Bhimavaram and Vijayawada.