This document by the Department of Environment, Government of Tamil Nadu highlights the importance of the Kodaikanal lake as an important tourist destination and warns that this freshwater lake is under the threat of getting polluted and its biodiversity endangered.

The document presents the findings of the study that aimed at assessing the physico-chemical and biological quality of the Kodaikanal lake.

Evidence indicates that unrestricted tourism activities have led to high use of plastic bottles, glass bottles, plastic bags, causing high levels of pollution and silting of the lake. Damaged fibreglass boats left inside the lakes also pose a serious threat to the lake ecosystem.

Besides this, other factors such as unrestricted cattle grazing along the banks of the lake also cause a threat to the quality of water and the biodiversity of the lake.

The study found that:

• The surface water pH of the lake water varied between 80.08-8.79 (Criteria C), the middle layered varied from 7.6 to 8.3 (Criteria C) and the bottom layer varied from 6.55 to 7.8 (Criteria A)
• The DO of the surface water varied from 4.7 to 6.9 mg/l (Criteria C), DO of the middle layer varied between 3.5 to 6.2 mg/l (Criteria C) and bottom layer varied form 2.4 to 4.8 mg/l.
• The BOD of the lake varied from 11 to14.62 mg/l
• The coliform count varied between 29 to 42 MPN/100 ml in the surface, middle and bottom layer
• The faecal coliform counts varied between 17 to 26 MPN/100ml in the surface, middle and bottom layers

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