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Karnataka’s polluted river stretches, a cause for concern

Last Updated : 25 February 2021, 20:11 IST

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Rivers are the lifelines of human civilisations. They were deemed as sacred since time immemorial by majority of the human civilisations. It is a known fact that almost all the civilisations flourished on river banks which shows how vital water is for our survival. Delhi on Yamuna, Bengaluru on Vrishabhavathi, Hyderabad on Musi, Chennai on Adyar, Lucknow on Gomati, Kolkata on Hooghly etc, are the notable few. In Karnataka too, several towns are established along the rivers - Mangaluru on Nethravathi, Shivamogga on Thunga, Karwar on Kali, Hosapete on Thungabhadra, and Honnavara on Sharavathi etc.

It is an irony that the rivers that we respect and pray are in a bad state of affairs due to various anthropogenic activities, though the magnitude of damage varies along the length of different rivers. Rapid industrialisation, urbanisation have led to discharge of untreated domestic sewage, industrial effluents, agriculture runoff, mining waste, construction waste, municipal solid waste etc, in to rivers.

Urbanisation adversely affects physical, chemical and biological aspects and life support system of river ecosystem. Landscape changes such as open vegetative spaces into impervious surface cover influence hydrology of a river basin leading into water quality deterioration and occurrence of frequent floods in the region. Urbanisation increases water temperature by directly discharging heated water from furnaces of industries into the rivers or by adding surface water runoff during summers increasing the microbial activity in river water.

Changes in the natural habitat of native flora and fauna of river basins, bio-diversity loss and impairment of ecosystem functions are the biological effects of urbanisation on river basins. Changes in land use patterns reduce species richness and decrease eco-system stability.

Chemical properties of the urban rivers get altered due to municipal and industrial discharges. Direct dumping of sewage and municipal solid waste into the river and addition of harmful chemicals from agricultural runoff contributes to river pollution.

Urban rivers are characterised by the presence of organic pollutants, high salinity, high Total Suspended Solid (TSS), heavy metals, nitrate, acidification and eutrophication, and high Biological Oxygen Demand (BOD) and Chemical Oxygen Demand (COD).

Based on the BOD value at the water quality monitoring locations along the river stretches, the Central Pollution Control Board (CPCB) has identified 351 Polluted River Stretches (PRS) throughout India wherein BOD exceeds 03 mg/L.17 PRS of them are in Karnataka under the catchment of 42 Urban Local Bodies (ULB).

Seventeen highly polluted river stretches in Karnataka are: Hunsur to Kattemalalvadi of Lakshmanatheertha, Thippagondanahalli Reservoir to Kanakapura of Arkavathi, Khanapur to Ramdurg of Malaprabha, Harihara to Haralahalli of Thungabhadra, Muller to Sattegala Bridge of Cauvery, Nanjangud to Hejjige village of Kabini, West Coast Paper Mill to Bommanahalli of Kali, Shahabad to Hongunta of Kagina, Yadurwadi to Junjarwadi of Krishna, Yalagur village to Narayanapura Bridge of Krishna, Bhadravathi to Holehonnur of Bhadra, Belur to Halavagilu of Yagachi, Yediyur to Halagur of Shimsha, Nethravathi and Kumaradhara, Ghanagapur to Yadgir of Bhima and Shivamogga to Kudli of Thunga.

Among the 17 PRS in Karnataka, 4 PRS are classified as Priority III in Lakshman Theertha, Arkavathi, Malaprabha and Thungabhadra (BOD in the range of 10 to 20 mg/L), six PRS are classified as Priority-IV in Cauvery, Kabini, Kali, Kagina, Krishna and Bhadra (BOD in the range of 6 to 10 mg/L) and 7 PRS in Yagachi, Shimsha, Nethravathi, Kumardhara, Bhima and Thunga classified as Priority-V (BOD in the range of 3 to 6 mg/L).

A basic inventory to identify the pollution source reveals that the 42 ULBs cumulatively generate 885 million litres per day (MLD) of sewage. Available total sewage treatment plant (STP) capacity in these ULBs is only 646.5 MLD. A total of 335.6 MLD of sewage is untreated which eventually enters the rivers making them highly polluted.

In addition to sewage, these 42 ULBs cumulatively generate 1860.7 tonnes per day of MSW. Of this, only 1672.5 TPD is collected and only 844.4 TPD is processed. Some 1016.3 TPD of MSW is accumulated in these river catchments threatening and damaging quality of river water.

Special interest

The Karnataka State Pollution Control Board (KSPCB) has taken special interest in the rejuvenation of the 17 PRS and facilitating the preparation of River Rejuvenation Action Plans for individual PRS along with complying timelines. The water quality is monitored on a regular basis by analysing the parameters such as pH, dissolved oxygen (DO), BOD, faecal coliform (FC) and total coliform (TC).

Under the River Rejuvenation Programme, 44 STPs with additional capacity of 341.116 MLD have been proposed. Among them, one STP of 5.5 MLD capacity in T. Narsipura ULB is under trial run, one STP of 35.58 MLD capacity in Shivamogga ULB is commissioned, nine STPs in Bengaluru (150 MLD), Dandeli (0.5 MLD and 8 MLD), Ramdurga (3.3 MLD and 1 MLD), Shivamogga (5.13 MLD), Bhadravathi (7.2 MLD, 5.3 MLD, 1 MLD) ULBs are under construction. The detailed project reports (DPR) have been approved for two STPs in ULB Bantwal (4.14 MLD and 0.22 MLD), DPR has been submitted for approval for eight STPs in Srirangapatna (1.4 MLD), Nanjangud (technology upgradation for the existing seven MLD plant), Hunasur (eight MLD), subramanya (2.6 MLD), Beltangadi (0.006 MLD), Belur (five MLD, one MLD) ULBs. A total of 23 STP DPRs are under preparation in Maddur, Hassan (five STPs), Ainapur, Khanapur, Soundatti (two STPs), MK Kanakapura (two STPs) and Honnali. For cities with less than 10 lakh population, faecal sludge and septage management facilities have been proposed in seven ULBs.

It is high time that sewage and SWM issues become top most priority of ULBs action. The pollution load should not cross the carrying capacity of rivers. The river rejuvenation programme of 17 polluted river stretches in Karnataka is aimed at improving river water quality so that benefit of life support system of sacred rivers is continuously available for future.

(The writer, who belongs to Indian Forests Service, is Member-Secretary, KSPCB)

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Published 25 February 2021, 18:45 IST

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