Surface (River) Water Pollution

Sewage Water

• Sewage water when discharges from houses, commercial and industrial establishments connected to public sewerage system.
• The sewage contains human and animal excreta, food residues, cleaning agents, detergents and other wastes.
• Domestic and hospital sewage contain many undesirable pathogenic microorganisms.
• However, about 70% of the effluents are not treated and disposed off into the environmental media untreated.

Industrial Wastes

• The industries discharge several inorganic and organic pollutants, which may prove highly toxic to living beings.
• Discharge of wastewater from industries like petroleum, paper manufacturing, metal extraction and processing, chemical manufacturing, etc.that often contain toxic substances, notably, heavy metals (defined as elements with density > 5 g/cm3 such as mercury, cadmium, copper, lead, arsenic) and a variety of organic compounds.
• Geogenic contaminants: salinity, iron, fluoride, and arsenic

Plastic bags are not biodegradable, clog waterways, spoil the landscape; break down into ever smaller particles that continue to pollute the soil and water.

• Agricultural runoff contains dissolved salts such as nitrates, phosphates, ammonia and other nutrients, and toxic metal ions and organic compounds.
• Excess fertilizers and pesticides may reach the ground water by leaching or may be mixed with surface water of rivers, lakes and ponds by runoff and drainage.
• Animal excreta such as dung, waste from poultry farms, piggeries and slaughter houses etc.  reach the water bodies through runoff and surface leaching during the rainy season.
• Huge amount of sediments caused by accelerated rate of soil erosion (such as deforestation) reaching the rivers is a major cause of nonpoint pollution.

1. Siltation of lakes due to dumping of enormous quantities of sediments due to accelerated rate of soil erosion.
2. Toxic effluents from the urban areas.
3. Washing and dumping of tailings or waste sludges from factories into stagnant water.
4. Inorganic nutrients from agricultural fields.
5. Acid rain: they are often called as‘Lake Killers’.

• It has become more or less a sewage tank because of untreated sewage water entering into the lake through various inlets. In theory, clean rainwater from Koramangala and Challaghatta (K&C) Valley should flow to Bellandur lake through stormwater drains. However, Bellandur lake gets sewage inflow due to two reasons.
• Improper sewage system due to which untreated sewage water overflows and joins stormwater drains, mixes with rainwater, which in turn flows to Bellandur Lake via Koramangala and Challaghatta Valley.
• Lack of effluent treatment plants to treat industrial wastes from small factories that also get into the stormwater drains.
• Fire at the lake: The cooking oil thrown from households that enters the lake from untreated domestic sewage is said to be the cause behind the fire.

• Desiltation of the lake is to eliminate contaminants.
• Stop all encroachments of the lake with suitable fencing
• Only stormwater should be allowed into the lake
• Army units should discontinue effluents from cattle house wash, cow dung wash, and army mess wash and consider the installation of a biogas plant.
• Plastic bags to be prevented from draining into the lake
• Sewage/manholes at identified locations to be closed.
• Drain water from slum around the lake to be treated before draining into the lake. Preferably, connect the slum stormwater and wastewater drain to the nearby Cox Town sewage drain as it is close to the slums
• Prohibit submergence of idols during the festival season
• Remove all slum dwellers from the region.
• Cultivate and harvest fish and aquatic plants to deplete the nitrogen and phosphate content