Kukkarhalli Lake

KUKKARHALLI LAKE: PRESENT CONDITION
Kukkarahalli Lake is spread over 58 hectares with a shoreline of roughly 5 kilometers in Manasagangothri, the sprawling campus of the University of Mysore. It is a freshwater lake with secondary scrub/dry deciduous forest. Mummadi Krishnaraja Wodeyar was responsible for getting the lake created, in the year 1864, to provide water for irrigation to 10,000 acres of land outside the city. The lake also used to be a source of water supply to the city of Mysore but over the years, sewage and excessive land encroachments (mostly illegal) and blockage of water flow sources almost lad to the eutrophication of the lake. The University of Mysore and the citizen forums of Mysore continue to make efforts to preserve the lake by implementing several remedial measures. The lake is great attraction to people who come for their health and are doing walking,jogging,cycling and yoga which provides a perfect natural environment for these activities but what about the health of the lake it is getting deteriorated day by day.There are many reasons responsible for this.

THE SOURCES OF POLLUTION IN LAKES ARE MAINLY IDENTIFIED AS:

 * Sewage entry from human settlements in catchment area.
 * Effluent entry from the industries located on the upstream of the lake.
 * Erosion of soil carrying nutrient from the upstream.
 * Ingress of sewage and industrial effluent which contains nutrient.
 * Runoff from surroundings areas which carries with it slit and nutrients.
 * For other human activities such as bathing, washing, disposal of garbage etc.
 * Dumping of debris from construction activity.
 * Immersion of idols during some festivals.

LAKE DEGRADATION
Over the years, the lake has deteriorated. What disturbed the lake? Majority of the lake water surface is covered with weeds. It is one of the reasons for the reduction in the bird’s population in the Kukkarahalli Lake.
 * Inflow of UNTREATED SEWAGE from Padavarahalli, Jayalakshmipuram, ontikoppal and Mysore University, Karnataka Open University into the lake.
 * Reduction of catchment area.
 * Indiscriminate dumping of SOLID WASTES.
 * Chocking of STORM WATER DRAINS.
 * Shrinking of FEEDER CANAL from 25 km to 5km due to urbanization.
 * Siltation.
 * Open defecation.
 * Every year there is a tradition of IMMERSING THE GANESH IDOLS in the lake and during this process, public dump the pooja materials like flowers, leaves, plastic, paper covers and coconuts in the lake. A part from sewage both organic and non degradable materials result in EUTROPHICATION ,thus depleting the dissolved oxygen amount in lake water, which helps to grow blue green algae like Microcystis aeruginosa which ultimately emanates foul smell.
 * In addition the idols are painted with colour which contain mercury, lead, chromium, arsenic and other harmful chemicals.

Some of the weeds which are found there:

 * Azolla

Environmental and other impacts: Azolla filiculoides forms dense mats and outcompetes native plant species. These infestations can reduce light levels below the mats and cause die of water plants and algae and reduce water oxygenation levels with serious impacts on fish and other fauna. Not only can very little survive under such conditions, but the quality of drinking water is reduced, caused by bad odours, colour and turbidity. A. filiculoidescan block canals, drains and overflows and may lead to an increased risk of flooding. . It is can also affect irrigations systems - both by blocking their water supply and by reducing water quality. The economic impact of A. filiculoides in South Africa was calculated by McConnachie et al. (2003). Among those water-uses most seriously affected were farming (71%), recreational (24%), and municipal (5%). On average, A. filiculoides was found to cause on-site damages of US$589 per hectare per year.


 * Salvinia

Effects on environment and others: The plant's growth clogs waterways and blocks sunlight needed by other aquatic plants and especially algae to carry out photosynthesis thereby deoxygenating the water. As it dies and decays, decomposers use up the oxygen in the water.It also prevents the natural exchange of gases between the air & the body of water the plant has invaded causing thewaterway to stagnate. This can kill any plants, insects or fish trapped underneath its growth. Its ability to grow and cover a vast area makes it a threat to biodiversity. Large infestations covering a wide area may also pose a problem to migratory birds as they may not be able to recognize an infested waterway when flying over head and so may not stop at it. Salvinia also provides ideal conditions for the breeding of mosquitoes that carry disease. The growth habit of Salvinia also is problematic to human activities including flood mitigation, conservation of endangered species & threatened environments, boating and irrigation.


 * Pistia (Jalkhumbi) 

Environmental effects: It forms a dense mat on the water surface and causes serious clogging on water ways. It is also responsible for harbouring mosquito larvae, which carry the filarial parasites. It flowers in hot season and fruits appear after the rain.


 * Wolffia

Environmental effects: The plants grow quickly and take up large amounts of nitrogen and phosphorus from the water. The plants that grow in the wastewater can then be used as feed for animals, such as carp, Nile tilapia, and chickens.

The samples of lake water were being collected and analyzed using standard methods for the examination of water. The analysis found that urbanization had produced a long term impact on the lake ecosystem and mostly contaminated by sewage mixing withlake water. Water hyacinth in Kukkarahalli had taken over with thick green crust. The weeds obstructed sunlight and reduced self purification action through photosynthesis. To maintain and prevent deterioration of water bodies, the following rehabilitation measures were proposed:
 * De-silting
 * De-weeding
 * Prevention of sewage and industrial effluents into the lake and construction of suitable effluent treatment plants.