Write a note on the major uses of lakes and with suitable examples highlight how human activities have adversely affected some of major lakes around the world. (200 Words)

Lakes are temporary features of the crust formed due to accumulation of water in hollows and are connected to rivers by outflows while percolation and evaporation happen as well. Lakes may be natural or man-made.
Lakes have been and are used for multiple purposes:
    1. Transport and Communication: Lakes provide means of easy transport for heavy and bulky items like coal, iron, etc. They also act as inland navigation routes. Example: The Great Lakes of North America.
    2. Supply of water: Lakes are mostly freshwater bodies. Their water is supplied for domestic uses, for agricultural and industrial uses as well. Initially most of the industries located near lakes for want of water supply and navigation.
    3. Moderating effect on climate. If lakes are large enough they produce same effect on climate as seas by means of breezes.
    4. Power generation and water flow regulation. Dams are constructed for power generation and they create artificial lakes for ensuring continuous water supply for power. Water can be diverted to agriculture as well. Example: Bhakra Nangal dam.
    5. Tourism and adventure activities are promoted in lakes as well. Many health resorts are near lakes. Also, ecology of lake is replete with many species.
    6. Salt and minerals can also be extracted from lakes. Example: Great Sambhar Lake of India.
However due to increasing usage of lakes by humans many environmental issues have come up:
    1. Excess use of fertilizers and run off of rain water has caused concentration of chemicals in lakes. This has damaged their ecosystem.
    2. Untreated sewage, industrial effluents and trash from cities are dumped. This causes degradation of water quality. Amount of dissolved oxygen is altered.
    3. Acid rain comes down into lakes as well. Our avenues of freshwater are getting disrupted.
    4. Due to chemicals in lakes, fishing activity is reducing. Also, these chemicals are entering our bodies due to bioaccumulation.
If unchecked, the lakes will suffer eutrophication and their surface will be covered by algae and slowly convert into swampy marshes and finally to wetlands. Examples: The Great lakes are suffering, Lake Powai water has been declared unfit for human consumption, and de-silting initiatives have been launched in lakes of Delhi as well.
What is Lake Rejuvenation?
It is the lowering down of the base level. In lakes and tanks it is usually done by cleaning in case of waste dumping and de-siltation in case of sedimentation in dams, so as to restore its original capacity of holding water.
Measures adopted to rejuvenate lakes and tanks in India:
    1. National lake conservation plan: The objective of the scheme is to restore and conserve the urban and semi-urban lakes and other unique freshwater eco systems of the country that are degraded due to waste water discharge, through an integrated ecosystem approach.
    2. Introduction of biological predator (insects, fungi, herbivorous fish) to remove the floating vegetation.
    3. Using wetland and spillway which will help mitigate sediment and nutrient flow in the lake from surrounding water sources.
    4. Mission kakatiya is a program of restoring all the tanks and lakes in Telangana State, India.
    5. Implementation of solid waste management rules 2016 also might help in lake rejuvenation
    6. Fixing the boundary of lakes and removal of encroachment.
    7. Diversion of sewerage water entering the lakes.
    8. New bund formation, strengthening of existing bund, waste weir improvement and de-silting to increase water storage
    9. Finally, while lake rejuvenation also involves fixing lake boundaries, fencing, de-weeding, de-silting, beautification, etc., all these are being addressed
    10. NGOs, including Reliance Foundation, and the corporate social responsibility arm of the construction company, Larsen and Toubro, are also excavating and cleaning some water bodies in some villages in Karnataka.
How will these measures benefit farmers?
    • Farmers are getting a bountiful supply of tank-bed soil to be used as top soil, as the government has taken up tank cleaning and dredging work. The top soil is good for agriculture as it is rich in organic matter and humus, besides cleaning of tank also increases their water holding capacity.
    • Covering Red soil fields with top soil will help farmers considerably. It will also help improve the water holding capacity of the waterbodies.
    • In the regions like Punjab where groundwater has been exploited rejuvenation of tanks works as a rain harvesting method where water is stored and provides water security.
    • Lakes that were unable to sustain any marine life due to silt, or shallow water levels were developed to support large scale fish farming.
These measures will provide water security and also have economic incentives in places where silt can be used for farming.