Lower Lake ASI-47

Lat.23.249 Lng.77.406 Alt.495
Riparian Nation(s) India
Surface Area 1 km2 Mean Depth 6.2 m Volume 0.008 km3
Shoreline 6.3 km Catchment Area 9.6 km2 Residence Time
Frozen Period None Mixing Type Polymictic Morphogenesis/Dam
Related Info/Site

Description

The findings indicate that the lake is highly eutrophicated and grossly polluted by continuous inflow of large amount of sewage badly affecting aquatic life. The lake gets high nutrient loading both from the bottom and the surface which creates complete anaerobic conditions in many parts even at a depth of one meter. The water remains very turbid throughout due to permanent algal blooms specially of Microcystis spp. In summer, water gets stratified with a difference of 9.8deg C but without well defined thermocline. Nutrients N & P; chlorophyll contents have increased many folds within a period of about ten years. Fecal bacteria population is very high indicating a high degree of contamination, with low fish production. The lake has a basic defect in its construction of the lower dam wall which is without a sluice gate and only aerated surface water continuously overflows the dam wall. Since, the lake is surrounded by the rows of houses within a hilly terrain the water remains stagnant without any circulation and mixing of the aerated and anaerobic bottom water and increases the sinking rate of the silt particles into the bottom. The whole lake is thus converted into a large septic tank making the lake shallower and shallower day by day. It has been recommended that all the sewage inflows should be diverted immediately to save its life span. The lake has great importance to local people, who take bath and wash their clothes because of scarcity of water. Water is also used for gardening but there is no well developed tourism because of the fowl odour of decaying algae (Q).

Photo of Lower Lake
Photo: S. Silakari