There is a marked deterioration in the quality of water in the Krishna River as it approaches the Krishna Delta. Water is drawn from the river to fulfil the drinking water needs of most of the population in Vijayawada and Guntur cities, Eluru, Gudivada, Machilipatnam besides thousands of villages in Prakasam, Guntur, Krishna and West Godavari districts.
The water from the river is diverted to these places through several canals that draw water from a reservoir at Prakasam Barrage. But the water in the reservoir is also polluted by several municipal sewerages that discharge directly into it.
The Biological Oxygen Demand (BOD), a pollution indicator of the water in the river, is on the rise, according to the Central Pollution Control Board. The average BOD of Krishna water has increased from 10 mg per litre in 2010 to 16 mg per litre in 2011. The board’s websites state that the average BOD of Krishna water is on the rise but the BOD figures for 2012, 2013 and 2014 are not made available.
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The average levels of two other indicators of water pollution — Coliform and Faecal Coliform bacteria — are also on the rise in the Krishna waters, according to the Board figures. The increase in Conductivity Value (yet another pollution indicator) is a real give away, say experts. A higher Conductivity Value indicates that there are more chemicals dissolved in the water.
There is a steep increase in the conductivity value of the river between Amaravati and Vijayawada. The maximum conductivity recorded at Amaravati increased from 796 millimhos per cm to 830 millimhos per cm in 2011.
Environmentalists say that the Krishna at Vijayawada is more like a reservoir because of the barrage. The chances of eutrophication are therefore high in post-monsoon and summer seasons because of direct dumping of sewage from thousands of dwellings on both the left and right flood banks.
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The Biological Oxygen Demand (BOD), a pollution indicator of the water in the river, is on the rise, according to the Central Pollution Control Board