 Modern day Vedaranyam has five fresh water channels from river Cauvery draining into the swamp . The total area of the swamp is about 349 km2 ( 135 sq mi ) , with 10 km ( 6 @.@ 2 mi ) width in the northwestern part and 6 km ( 3 @.@ 7 mi ) width in the western side . The Kodikarai wildlife reserve is located in the extreme eastern portion of the swamp . The northern tip of the swamp obtains continuous source of fresh , saline or brackish water during the south west monsoon and dries up during the summer season . The swamp is used for salt extraction and other marine based industries . The swamps are filled by two periodical high tides that occur during the full moon days of May and June . The swamp along with the sanctuary is the important wintering and staging area for waders and water birds . 
