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6. Opportunities and Initiatives for Restoration

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Efforts towards lake restoration and conservation in Bangalore are piecemeal and reactive. Conservation efforts could be far more effective if we could avoid habitat degradation. This approach would require an ability to predict the elements of the lake biota that are most vulnerable to extinction and to identify their ecological attributes (bird migration, fish diversity, etc.). A related point is the need to assess the health of the lake community and to monitor changes in it over time. The preliminary step that has to be implemented in restoring lake for their long-term sustenance includes:

1. Pollution impediment : Wastewater, solid and semi solid wastes entering in to the lake from external sources must be stopped before any restoration work is implemented.
2. Harvesting of Macrophytes : Water hyacinth and other nuisance vegetation present in the lake, causing eutrophication, must be removed manually or mechanically. Weed infestation can also be controlled by applying chemicals like methyl-chlora-phenoxy-acetic acid, hexazinore, etc., and biological control by means of introducing Pila globosa (trophical snail), Chinese grass carp (fast growing fish) etc. that feed on many aquatic plants.
3. Desiltation : Dredging of the sediments in the lake to improve the soil permeability, water holding capacity and ground water recharge. Recent technological developments do permit wet dredging. Studies in Kolar district reveal that desilting of waterbodies helps in improving the groundwater table while lowering fluorides contamination in groundwater.
4. Rain water harvesting : The lake can also be used as rainwater harvesting structure. After desiltation or dredging, the storage capacity i.e., the water holding capacity of the lake would increase and as Varthur lake has a large catchment area, it would prove to be an effective rainwater harvesting structure. The bunds surrounding the lake can be strengthened and fencing should be provided around the lake. A draw well can be constructed at one end of the tank with an underground filter media connecting the well and tank bed to fetch clear water.
5. Watershed Management : Watershed management is the rational utilisation of land and water resources for the optimum production with minimum hazard to natural resources. As an extension of the restoration programme, watershed management practices are essential for proper land use, protecting land against all forms of deterioration, conserving water for farm use, proper management of local water for drainage, flood protection and sediment reduction and increasing productivity from all land uses.
6. Best Management Practices : The restoration programmes with an ecosystem approach through Best Management Practices (BMPs) helps in correcting point and non-point sources of pollution. Key steps for best management practices include:
   • Pollution alleviation practices to reduce the engendering of non-point source of pollution (mainly agricultural and storm runoff) through source reduction, waste minimisation and process control.
   • Promoting public education programmes regarding proper use and disposal of agricultural hazardous waste materials and regular monitoring of lakes, which are rudimentary. The local schools can undertake the periodic monitoring of water bodies and educating the stakeholders on the importance of restoration and maintenance of the Varthur lake.
   • Afforestation with native species in desolate areas in the catchment area to control the entry of silt from run off.
   • The shorelines of the lakes should be lined with bricks or stones to control shoreline erosion.
   • Constructed wetlands for the purpose of stormwater management and pollutant removal from the surface water flows.
   • Infiltration trenches for reducing the storm water sediment loads to downstream areas by temporarily storing the runoff.
   • Extended detention dry basins for removing pollutants primarily through the settling of suspended solids.
   • Gyration of crops rather than monocultures to reduce the need for N and assist with pest control and help in aeration of soil

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