Morphometric, physical and chemical charaterisation of the lake revealed that :
- The morphometric survey showed that the lake occupies an area of 1 478 000 m2 with a
mean depth of 1.05m. The morphometric results emphasise the fact that the whole of
Varthur lake is shallow in relation to its surface area.
- The results of the water quality analysis show that the lake is eutrophic with high
concentrations of phosphorous and organic matter. All the parameters analysed were
above the standards prescribed for surface waters. The lake was also subjected to faecal
contamination. The groundwater analysis did not reveal any contamination by lake water,
but further analysis has to be undertaken to rule out the possibility of groundwater
pollution.
- Nutrient enrichment is largely responsible for the poor quality and Varthur lake displays
many features common to eutrophic water bodies, such as low dissolved oxygen levels
and high ammonia content, which result in a reduction in the diversity and number of
animal species that can inhabit a lake. Nutrient and organic pollution is likely exacerbating
problems like plant overgrowth, pathogenic bacteria, increased mosquito populations, and
unappealing smell. The most significant source of this pollution is due to inflow of
untreated sewage of the Bangalore city.
- The socio-economic aspects of Varthur lake showed that local residents continue to
rely heavily on the lake for cattle fodder and irrigation. It is obvious that Varthur lake
continues to provide substantial economic benefits to the local population, despite the
tendency of some locals to avoid direct contact with the lake due to the previously
mentioned health risks and aesthetic concerns. Factors that elude quantification through
a socio-economic surveying, such as microclimate regulation, biodiversity, and the rich
heritage associated with the lake, add to the value of this resource. All of these benefits
are being eroded by contamination of the lake and, therefore, lake restoration must take
place in order to maintain and, perhaps, improve the quality of life currently available to
residents of the Varthur lake area. A majority of residents in the area recognise the
importance of the lake and are willing to offer their support for such efforts.
