The Keezhkattalai Lake, one of Chennai’s prestigious lakes, is divided into two parts – South and North – with State Highway 109 running through. Home to diverse bird species and aquatic life, the lake faces a significant threat from sewage and non-biodegradable waste.

About lake:

1. The Lake is located on the arterial Pallavaram-Thoraipakkam radial road in South Chennai
2. The lake is a significant storage zone before the Pallikaranai marsh
3. With its catchment from the western periphery, the lake is currently split by the road into two portions
4. Restoring this lake will make it a critical habitat for dependent life forms
5. The lake is a significant flood barrier
6. A localized water reserve catering to the direct population of nearly 55,000 residents

Problem statement:

1. No proper boundary –  The water bodies had undefined boundaries with no definitive foreshore
2. Abuse & Exploitation of Lakes  – 
   1. Incessant dumping of domestic and construction waste
   1. The inflow of untreated sewage and road runoff leads to eutrophication
3. Lacks Structural Integrity –
   1. The uneven contour of the lake bed
   1. Improper embankment system, posing threat of flooding
4. Growth of Invasive Weeds –
   1. Owing to no proper maintenance, the lake has a rampant growth of invasive weeds
   1. Weeds such as Prosopis juliflora, Lantana camara, Parthenium and Ipomoea carnea were found across the lake
5. Risk of Encroachment – Being unprotected, with no boundary system in place, the lake is vulnerable to being encroached on shortly

Before restoration pictures: Overgrowth of invasive weeds along the boundaries, excessive dumping of construction debris and eutrophication of the lake were found before restoration.

The lake can be seen lacking a proper boundary, that either has damaged or non-existent bunds in place that would have helped in storing water effectively.

De-weeding:

1. Over the years, the lake owing to sheer negligence and no maintenance had witnessed a rampant growth of invasive weeds.
2. An effort aimed at eliminating invasive vegetation from the water bodies.
3. Invasive vegetation such as Prosopis juliflora, water hyacinth and Ipomea were widespread across the water-holding area of the lakes. Eliminating these was important before the deepening activities.
4. Invasive vegetation sucks more groundwater and grows faster taking over the lake landmass and rendering it unusable for water storage
5. It is important to clear these invasive weeds as they tend to dominate native species that play an important role in maintaining the balance in an ecosystem.
6. A total area of 70,957.5 sq feet was during this activity and was done with the help of excavators

Schematic representation De-weeding area

De-silting :

1. The lakebed comprises silt, with the upstream erosion that often causes siltation in the downstream catchment. Over some time, considerable silt deposition would reduce the storage area of the water holding zone.
2. Excess silt deposition leads to shallow storage points thereby wasting precious freshwater during the monsoons
3. Timely desilting and deepening of the water body is crucial for maintaining optimum storage, and effective groundwater recharge

Schematic representation De-silted area

Informative awareness boards: To enhance public awareness, boards featuring bird illustrations were installed in both sections of the lake, facing the roads, providing visitors with a glimpse into the avian diversity of Keezhkattalai Lake, akin to a miniature bird museum.

  Project updates to date:

• Deweeding in the Southern lake along the North-East-South axis
• A total of 2 tonnes of invasive weeds such as Prosopis juliflora, and overgrown thorny shrubs were removed with the help of machinery for a length of 2,247 feet.
• Deweeding in the Northern lake along the Western periphery
• A total of 1.5 acres was cleared of invasive weeds along the Western periphery
• Removal of construction debris weighing nearly 3 tonnes was cleared from the Lake
• Bund formation in the Northern lake along the Western axis –  60 % completed covering a distance of 426 feet.
• The effect of monsoons and cyclones is currently being assessed and monitored at the lake

Volunteer for India and her Environment with E.F.I