The Heen Ela marsh is situated near the Rajagiriya town in the Sri Jayawardenapura DS area. At present the land area of the marsh is about 115 acres (46 Hectares) including 4 islands being 6.5 acres in size. The area of the water bodies around the marsh is about 34 acres. During the early stages the land had been cultivated with paddy and thereafter abandoned in 1977. After which the paddy land converted slowly into a rich marsh land. An early study of the marshland (year 2003) identified 86 birds of which 35 species were aquatic. There are several important flagship aquatic species in the marsh including the fishing cat (endangered), the otter and Estuarine crocodile (endangered).

SLLRDC has excavated a canal from 2 sides isolating the marsh and this activity has stopped the encroachment of this land by the people.

The invasive wel-atta (annona glabra) trees have now invaded about 40-45%, Acacia auriculiformis also grown among Wel-atta of the Heen Ela marsh and the rest of the area (i.e. approx. 55-60%) is covered by over grown grass, shrubs and herbs. This land in risk due to situated bordering to Colombo city limits which highly valuable for a mega development project.

This project is proposed to create suitable habitats to attract aquatic birds and open to the visitors to ensure to protect the marshland. The declining population of aquatic birds and other fauna due to habitat loss will increase after the habitat restoration.