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Session 4Limnology of Lakes, Reservoirs and Wetlands

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Chairman: Dr. Chakrapani B. K.

Rapporteur: Sudira H. S

Pollution of Ooty Lake and Restoration

Meenambal T.


Ooty is one of the most important hill stations in Tamil Nadu. It has a beautiful lake located 2.6km from Vannarpet called as Ooty lake.  This lake is more than a century and a half old.  It was formed by blocking a maintain stream.  It has a shoreline of 5km long and has a maximum depth of 15m.

 The Ooty lake receives its water from the surface runoff in the following areas; past of larks Hill, St. Mary’s Hill, Missionary Hill, Fern Hill and Elk Hill.  Besides the above runoff a perennial stream from upper Koddappamund Hills joins the lake.  At Ooty the stream joins the Ooty channel which in turn joins the Ooty lake at the south end of the lake.  About 2.6 km length of the channel receives almost all the polluting material, which are passed on to the lake. The major pollutants which are receiving from  the untreated dairy waste products, unsewered waste water from the Public, oil and grease form workshops and sullage from railway colony and near by area joins the channel in large quantities a few metres before its tail end.  Due to the discharging of sullage water in to the lake, the excessive water hyacinth and algal growth in the water body leads to eutrophication. At present the lake water is green in colour and has an algal odour.  Due to the wastewater from the workshops, the south end of the lake water is highly polluted than the other pouts of the lake.  So we have to adopt source restoration methods to rate guard are existing natural lakes.

 The restoration methods are as follows

  1. Total elimination of external loading: It means that the channel feeding the lake is totally free from any sewage, sullage and dairy waste etc. All the unsewered systems should be properly sewered.

  2. Aeration of lake water: Pumping of hypolimnic water to the surface, where it is aerated by contact with the atmosphere and transported back to the hypolimnion.  This process is required for reducing oxygen depletion in the hypolimnion due to decomposition of organic matter.

  3. The quality of the lake water should be monitored by measuring at fornightly intervals important parameters like DO, BOD, COD, oil and grease, turbidity etc.

  4. Entry of materials containing nitrogen and phosphorus should be prevented.  Unless eutrophication is arrested immediately the lake may end up as a marsh.

  5. Educating the lay public on the need to maintain a clean environment is important.

Address:  Govt. College of Technology
Coimbatore 641 013. Tamil Nadu, India