Environmental Pollution: Water Pollution

Dissolved oxygen (DO): Refers to the level of free oxygen present in water. Optimum DO content in water is important for the survival of aquatic organisms
Biological Oxygen Demand (BOD): It 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. It is expressed in milligrams of oxygen per litre of water.
Chemical Oxygen Demand (COD): It measures the amount of oxygen in parts per million required to oxidise organic (biodegradable and nonbiodegradable) and oxidisable inorganic compounds in the water sample.

Industrial Discharge: Factories release untreated or inadequately treated effluents, including heavy metals, toxic chemicals, and organic pollutants, into rivers and lakes.
Domestic Sewage: Urban areas generate large volumes of sewage that often flow untreated into water bodies due to inadequate sewage treatment infrastructure.
Agricultural Runoff: Use of chemical fertilisers, pesticides, and insecticides in agriculture results in runoff that contaminates surface and groundwater.
Solid Waste Dumping: Improper disposal of solid waste, including plastics and other non-biodegradable materials, leads to the clogging and contamination of water bodies.
Mining Activities: Mining operations discharge pollutants, including heavy metals and suspended solids, into nearby water sources.
Oil Spills: Accidental oil spills and leakage from oil pipelines contribute to significant water pollution, particularly in coastal areas.
Religious and Cultural Practices: Rituals involving the immersion of idols and disposal of religious offerings contribute to pollution, especially during festivals.

Public Health: Contaminated water can cause waterborne diseases like cholera, typhoid, diarrhoea, and skin infections. These diseases disproportionately affect children and communities relying on polluted water sources.
Aquatic Ecosystem: Pollution disrupts the delicate balance of aquatic ecosystems, leading to fish kills, biodiversity loss, and degraded habitat quality.
Agriculture: Salinity intrusion due to overexploitation of groundwater and pollution can render agricultural land unsuitable for cultivation.
Livelihoods: Fishing communities and those dependent on tourism near polluted water bodies suffer economic losses due to declining fish populations and a degraded environment.

Ganga Action Plan (GAP): First river action plan taken up by MoEF in 1985 as a centrally sponsored scheme. It was partially successful and closed in 2002 making a significant difference to water quality.
National River Conservation Plan (NRCP): Provides financial/ technical assistance to the States/UTs on cost sharing basis to bring the river to bathing quality standards. It included treatment of raw sewage before flowing into the river, Prevention and control of industrial pollution, Electric crematoria to ensure proper cremation of bodies brought to the burning ghat and Riverfront development works such as improvement of bathing ghats, etc.
National Ganga Council: Established by the River Ganga (Rejuvenation, Protection, and Management) Authorities Order, 2016. It replaced the National Ganga River Basin Authority (NGRBA) headed by the Prime Minister.
Namami Gange Programme(2019) : The main pillars of the programme are Sewerage Treatment Infrastructure, River-Front Development, River-Surface Cleaning, Biodiversity, Afforestation, Public Awareness, Industrial Effluent Monitoring and Ganga Gram.
Swachh Bharat Mission (SBM, 2014): It is implemented by the Ministry of Drinking Water and Sanitation (Ministry of Jal Shakti from 2019). SBM seeks to achieve universal sanitation coverage by making Gram Panchayats Open Defecation Free (ODF). Under SBM, incentives are provided for the construction of household latrines.