Kodaikanal Lake, also known as Kodai Lake is a manmade lake located in the Kodaikanal city in Dindigul district in Tamil Nadu, India. Sir Vere Henry Levinge, the then Collector of Madurai, was instrumental in creating the lake in 1863, amidst the Kodaikanal town which was developed by the British and early missionaries from USA. The lake is said to be Kodaikanal's most popular geographic landmark and tourist attraction.
Over the years a boat club, boathouse and boat service (with rowing boats and pedalling boats and a public ferry) for the public and tourists has become fully functional and is of aesthetic significance for tourism. Boat Pageant and Flower Shows are a regular feature in the summer season which attracts tourists.
A railway line extended from Chennai to Tirunelveli with an intermediate station at Ammaianayakkanur (later renamed Kodai Road) was built in 1875, to provide a gateway to Kodaikanal town and there on to the lake through a foot trek of 18 km from the railhead. The nearest railheads to the lake presently are the Kodai Road railway Station at 80 km and the Palani Railway station at 64 km distance, from the town. Madurai (at 121 km) and Coimbatore (at 135 km) airports are the closest to the Lake. Kodai Lake is well connected by road with regular bus services operating to Madurai, Palani, Kodaikanal Road, Theni, Dindigul, Thiruchirapalli, Kumili, Erode, Bangalore and Coimbatore.
An earthen dam was constructed to create the lake in a marshy where three streams flowed. The lake catchment experiences an average annual rainfall of 1650 mm. The climate is salubrious with summer temperatures of 19.8 °C (max) and 11.3 °C (min) and winter temperatures of 17.3 °C (max) and 8.3 °C (min). The out flow from the Lake forms the waterfall of 180 foot, called the Silver Cascade, 8 km downstream of the lake outlet.
Kurinji (Strobilanthes kunthiana), a unique flowering plant is reported from the catchment area of the Lake. It is reported that this flower last bloomed in 2004 and that it blooms once in 12 years. Hill-plantain fruits and plums are popular in the area.
The lake is star-shaped, centrally located in the town of Kodaikanal and is surrounded by lush green hills of the northwestern Palani Hills range, which is the main watershed for the lake.
The Lake has moderate to dense growth of macrophytes of all types. The littoral zone of the lake is reported to be rich in periphytic biota associated with macrophytes. Diatoms, protozoans and rotifers which are also associated with macrophytes are found in the lake. Many aquatic insect larvae and adults, molluscs, cladocerans and the fish Danio aequipinnatus, Rasbora daniconius and Gambusia affinis are reported. Rainbow trout and common carp are the main fish found in the lake. The fish yield as per past records was 5.3 kg/ha/year. Recently two new species of diatom was found in this lake.