Pulicat Lake - Threats To The Lake

Threats To The Lake

In the Andhra Pradesh part of the lake several threats to the lagoon have been identified. These are: pollution from sewage, pesticides, agricultural chemicals and industrial effluents – from Arani and Kalangi rivers draining into the lake that bring in fertilizers and pesticides with the runoff from the agricultural field in to the drainage basin, domestic sewage, effluents and wastes from numerous fish processing units; oil spills from the mechanized boats; release of4,780 hectares (11,800 acres) of the Sanctuary for a marine chemicals and salt-manufacturing industry and shrimp farming in more than 1,000 acres (400 ha) on the eastern part of the lagoon have affected the Pulicat Bird Sanctuary; livelihood of 30,000 fishermen and 20,000 agricultural labourers (for whom fishing is an off-season economic activity) have also been disturbed. This activity is also reported to have serious impact on aquaculture development.

Threats to the Tamil Nadu part of the lagoon are from two major sources. These are siltation and pollution.

Siltation and periodic closure of the bar mouth due to the dynamic process of sediment transport has caused reduction of size and seasonal closure of the mouth of the lake has reduced fresh sea-water exchange and made the lake shallow and turbid. It is reported that average depth of 1.5 metres (4.9 ft) in the early 20th century, has reduced to less than about 1 metre (3.3 ft) now, in the lagoon. This has caused difficulties such as mouth getting silted up and getting closed during the summer season (June–July to Oct–Nov); raise in flood level occurs during the rainy season; the lake acts as a large evaporating basin when the bar is closed resulting in salinity levels remaining low or high subject to the flood discharge into the lake during the northeast monsoon; fluctuation of water level in the lake (above or below the sea level) is affecting flora, fauna and fisheries; siltation has caused variation of the lake mouth resulting in reduction of tidal inflows and consequent decline in stocking of commercially important species of prawns and mullets.

Pollution and Human Impacts are: the Arani and Kalangi rivers carrying runoff from agricultural fields in the drainage basin cause increase in pollution load from fertilizers and pesticides into the lake; pollution from domestic sewage being released to the lake; Petrochemical complex, power plant and a satellite port on Ennore creek have further aggravated the problem; there is threat of flooding of 14 island – villages of the lake; subsequent to the Tsunami in 2004, the number of fishing boats have increased resulting in the `Catch Per Unit Effort' of fish, prawns and crabs declined from 1000 tonnes to about 700 tonnes; and this has increased the social and fishing rights conflicts between marine based fishermen and the lagoon fishermen.

Due to the 2004 Indian Ocean earthquake, lagoon fishery was adversely affected, with many fishing communities losing all means of livelihood until the middle of April 2005, as the loss of lives, homes and boats prevented them from going fishing in the sea and the lake. They subsisted on relief supplies provided by the government and other agencies. Many people in fish related trades were also affected. However, a beneficial effect of the tsunami has been the widening of the opening to the lagoon.