There is a salt water barrier at Thanneermukkom, built across the lake, which connects it to Vechoor in Kottayam district.

This barrier essentially divides the lake into two parts - one with brackish water perennially and the other half with fresh water fed by the rivers draining into the lake.

This barrier has helped the farmers in Kuttanad - where farming is done below sea level.

The backwaters which were abundant with fish and part of the staple food of the people of the region require a small amount of salt water for their breeding.

The salt water barrier has caused deterioration of the catch of fish in the region and the fishermen are opposed to the bund as of 2005.