Pulicat lake, the second largest waterbody in the country next only to Chilka in Orissa, is facing severe degradation and rapid reduction in size owing to natural and human activities, a recent survey has revealed.

The lake, also called Pazaverkadi lagoon, extends between South Andhra Pradesh and North Tamil Nadu, about 80 km north of Chennai.

More than 60,000 migrant water birds feed and breed in the northern part of lake during winter. About 40,000 people living in 34 villages on the banks Pulicat on the Tamil Nadu side, depend directly or indirectly on the lake.

The findings, conducted by an expert team from the Loyola Institute of Frontier Energy under the 'Pulicat Community Based Disaster Preparedness' project revealed that the lake which once extended to 460 square km has been reduced to 350 square km in a few decades leading to a huge reduction in the aquatic population.

This was due to rapid shrinking of the water spread area mainly due to silting in the northern part of the lake, it said.

"Earlier the depth of the lake used to be four meters, but now it is 1.5 meters. Reduction of water has led to lower aquatic life," Chief co-ordinator of the project Dr Selvanayagam said.

He said during summer, the sea water inflow recedes to a thin line, affecting the flow into the lake. Evaporation due to summer heat saturates the salinity of the lake water.