Situated about nine km from Thiruvananthapuram Central Railway Station, the approximate spread of the lake is around 1,853 acre, but due to encroachment, it has shrunk to a mere 428 acre.
The lake is a prime source of drinking water in the district and has a unique ecosystem featuring some of the rarest birds, fish and flora, said Abey George, Secretary of Swasthi Foundation which has spearheaded plans for rejuvenating the lake.
In May, the process of de-weeding was started using mechanical weed harvesters. So far, one third area of the lake has been cleared of weeds and dredging will begin shortly, he said.
"The de-silting operations with the help of the Irrigation Department will add a mean depth of 1.5 meters to the lake and increase its storage by nearly three times. After dredging, bio- and phyto-remediation will be implemented to improve the water quality, which has been adversely affected in recent times," George added.
He said the work is expected to finish in another 150 days and once that is done, the State Tourism Department will step in and promote the site as a tourism spot with activities like a walkway around the lake, aqua sporting activities, and fishing.
A survey was also conducted covering all aspects of the lake - its existence, factors contributing to its deterioration, effects on local life, water quality, water table, biodiversity and fauna.
The efforts are supported by private organisations and the government also provides technical and administrative help.
State Irrigation Minister, K. Krishnan Kutty, early this week visited the lake and applauded the work being done there.
"The state government will play its role and has begun issuing tenders to buy a state-of-the-art equipment from the Netherlands, which is to be used to clean lakes," said Kutty.
A former official of the Kerala State Biodiversity Board, K.P. Laladhas, said people's participatory approach is essential for the successful conservation of any natural ecosystem and the Vellayani ecosystem is an abode for indigenous and migratory birds.
( With inputs from IANS )