Context: Recently, the Forest and Environment Minister of Karnataka, revealed that 16 rivers in Karnataka are polluted.

Rivers in Karnataka Highly Polluted

• Major rivers in Karnataka, including Arkavati, Lakshmana Tirtha, Tungabhadra, Bhadra, Tunga, Kaveri, Kabini, Kagina, Krishna, Shinsha, Bhima and Netravati had found their names on the list of polluted water bodies. 
• The concentration of biochemical oxygen demand (BOD) in River Arkavati had soared to more than 30 milligrammes per litre, making it the most polluted river in the state.
• Tungabhadra, Bhadra, and Shinsha rivers, grappling with BOD concentrations of 6-10 mg per litre, were also distressingly contaminated. 
• The remaining eight rivers had relatively lower BOD levels in the 3-6 mg per litre range.

River Pollution: Causes

• Sewage and Discharge: 
  • Industrial Discharge: Factories and industrial plants often discharge chemicals and toxic waste directly into rivers.
  • Urban Runoff: Urban areas contribute pollutants such as oils, grease, heavy metals, and other chemicals through stormwater runoff.
  • Agricultural Runoff: Fertilizers, pesticides, and herbicides used in agriculture can run off into rivers, especially during rainfall. This runoff can increase nutrient levels in the water, leading to eutrophication.
• Deforestation: Removing trees along riverbanks can increase erosion rates, leading to more sediments and pollutants entering rivers.
• Airborne Pollutants: Pollutants from the air can settle in rivers. This includes particulate matter from vehicles, industries, and natural sources like volcanic ash.

Way Forward

• Establishment of Sewage Treatment Plants: The Karnataka government established 24 Sewage Treatment Plants (STP) strategically placed to purify the contaminated water.
• Citizen Participation and Coordinated effort: Need for sustained public awareness, community involvement and stricter enforcement of environmental laws.
• Enhancing Underground Drainage Systems: The underground drainage systems require significant enhancements to improve efficiency and effectiveness. 
  • For Example: the Karnataka State Pollution Control Board (KSPCB) emphasized enhancement for municipalities and panchayats to actively engage in the establishment of robust underground drainage systems and STPs. 

News Source: Down to Earth