The Yamuna catchment area of the National Capital Territory is one per cent of the river's total catchment area but it generates more than 50% of the pollutants found in the Yamuna. The crucial stretch is a mere 22-km-long portion of its 1200 kilometre journey. Waste water with little or no oxygen flows through this stretch. TERI studies say that more than 70% of the 84 districts that make up the Delhi sub-basin, are water-stressed due to depletion and degradation of quality of ground and surface water resources. Delhi receives relatively clean water and converts it into a deadly concoction of disease-bearing water for the people who live downstream.
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| Eighty per cent of the districts suffer because of that 22-km stretch where effluents pour into the river. Yamuna before the Wazirabad stretch has appreciable levels of dissolved oxygen, low biochemical oxygen demand levels and the water is extensively used for irrigation purposes. Haryana, Himachal Pradesh and parts of Uttar Pradesh use 6000 million metres cubic water every year for irrigation. The scene changes dramatically once the waters reach Delhi. None of the cities downstream generate more than 1000 MLD (million litres per day) of waste water. In contrast, Delhi alone generates 3000 MLD of waste water. | |
Bacteriological count - an indicator of the presence of pathogens - is under permissible level upto Delhi. The Delhi region makes this count dangerously high. This means that Delhi could be responsible for all water-borne diseases caused by use of Yamuna waters beyond Delhi.
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Delhi is also responsible for the low income group and incidentally the high risk group which resides on the river banks. Though Delhi collectively contributes to the pollution of the river, more than 750 000 colonies along the 22 km stretch bear maximum brunt of the river's waters.
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Significantly, even as Delhi generates more than 3000 MLD of waste water, generally most of its sewage treatment plants function erratically. This simply means that this waste water enters the Yamuna without undergoing purification! Poor designing and frequent power cuts are mainly responsible for this state of affairs.
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Large quantities of complex organic pollutants are broken down by aquatic microorganisms who consume dissolved oxygen for this purpose from the waters. This results in depletion of oxygen and hence acute deficiency of oxygen for other riverine organisms such as fish. Plainly speaking, no oxygen means very less life is possible in these waters and the Yamuna becomes a dead river.
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