16 Rivers in Karnataka Highly Polluted: Revealed by Forest and Environment Minister of Karnataka

GS Paper III Environment

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.

Biological Oxygen Demand:

Biochemical oxygen demand (BOD) represents the amount of oxygen consumed by bacteria and other microorganisms while they decompose organic matter under aerobic (oxygen is present) conditions at a specified temperature.
Indicator of Organic Pollution: BOD is used to gauge the level of organic pollutants in rivers, lakes, and streams. High levels of BOD indicate a high concentration of biodegradable material, often due to pollution.
Significance for Ecosystem Health: Low levels of BOD are usually an indicator of good water quality, suggesting the water body can support a healthy ecosystem. High BOD levels deplete oxygen, leading to anoxic conditions harmful to aquatic life.
Application in Wastewater Treatment: BOD analysis is crucial in wastewater treatment processes. It helps in assessing the effectiveness of treatment methods in removing organic waste.

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.

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.