India’s 14 major, 55 minor and several hundred small rivers receive millions of litres of sewage, industrial and agricultural wastes. The most polluting source for rivers is the city sewage and industrial waste discharge. Presently, only about 10 per cent of the waste water generated is treated; the rest is discharged as it is into our water bodies.
Causes of water pollution:There are several classes of common water pollutants. These are disease-causing agents (pathogens) which include bacteria, viruses, protozoa and parasitic worms that enter water from domestic sewage and untreated human and animal wastes.
Human wastes contain concentrated populations of coliform bacteria such as Escherichia coli and Streptococcus faecalis. These bacteria normally grow in the large intestine of humans where they are responsible for some food digestion and for the production of vitamin K. These bacteria are not harmful in low numbers.
Large amounts of human waste in water, increases the number of these bacteria which cause gastrointestinal diseases. Other potentially harmful bacteria from human wastes may also be present in smaller numbers. Thus, the greater the amount of wastes in the water the greater are the chances of contracting diseases from them.
Another category of water pollutant is oxygen depleting wastes. These are organic wastes that can be decomposed by aerobic (oxygen requiring) bacteria. Large populations of bacteria use up the oxygen present in water to degrade these wastes. In the process this degrades water quality.
The amount of oxygen required to break down a certain amount of organic matter is called the biological oxygen demand (BOD). The amount of BOD in the water is an indicator of the level of pollution. If too much organic matter is added to the water all the available oxygen is used up.
This causes fish and other forms of oxygen dependent aquatic life to die. Thus, anaerobic bacteria (those that do not require oxygen) begin to break down the wastes. Their anaerobic respiration produces chemicals that have a foul odour and an unpleasant taste that is harmful to human health.
A third class of pollutants are inorganic plant nutrients. These are water soluble nitrates and phosphates that cause excessive growth of algae and other aquatic plants. The excessive growth of algae and aquatic plants due to added nutrients is called eutrophication. They may interfere with the use of the water by clogging water intake pipes, changing the taste and odour of water and cause a build-up of organic matter.
As the organic matter decays, oxygen levels decrease and fish and other aquatic species die. The quantity of fertilizers applied in a field is often many times more than is actually required by the plants. The chemicals in fertilizers and pesticides pollute soil and water. While excess fertilizers cause eutrophication, pesticides cause bioaccumulation and biomagnification.
Pesticides which enter water bodies are introduced into the aquatic food chain. They are then absorbed by the phytoplankton and aquatic plants. These plants are eaten by the herbivorous fish which are in turn eaten by the carnivorous fish which are in turn eaten by the water birds. At each link in the food chain these chemicals which do not pass out of the body are accumulated and increasingly concentrated resulting in biomagnification of these harmful substances.
One of the effects of accumulation of high levels of pesticides such as DDT is that birds lay eggs with shells that are much thinner than normal. This results in the premature breaking of these eggs, killing the chicks inside. Birds of prey such as hawks, eagles and other fish-eating birds are affected by such pollution. Although DDT has been banned in India for agricultural use and is to be used only for malaria eradication, it is still used in the fields as it is cheap.
A fourth class of water pollutants is water soluble inorganic chemicals which are acids, salts and compounds of toxic metals such as mercury and lead. High levels of these chemicals can make the water unfit to drink, harm fish and other aquatic life, reduce crop yields and accelerate corrosion of equipment that use this water.
Another cause of water pollution is a variety of organic chemicals, which include oil, gasoline, plastics, pesticides, cleaning solvents, detergent and many other chemicals. These are harmful to aquatic life and human health. They get into the water directly from industrial activity either from improper handling of the chemicals in industries and more often from improper and illegal disposal of chemical wastes.
Sediment of suspended matter is another class of water pollutant. These are insoluble particles of soil and other solids that become suspended in water. This occurs when soil is eroded from the land. High levels of soil particles suspended in water, interferes with the penetration of sunlight. This reduces the photosynthetic activity of aquatic plants and algae disrupting the ecological balance of the aquatic bodies.
When the velocity of water in streams and rivers decreases the suspended particles settle down at the bottom as sediments. Excessive sediments that settle down destroys feeding and spawning grounds of fish, clogs and fills lakes, artificial reservoirs etc.
Water soluble radioactive isotopes are yet another source of water pollution. These can be concentrated in various tissues and organs as they pass through food chains and food webs. Ionizing radiation emitted by such isotopes can cause birth defects, cancer and genetic damage. Hot water let out by power plants and industries that use large volumes of water to cool the plant result in rise in temperature of the local water bodies.
Thermal pollution occurs when industry returns the heated water to a water source. Power plants heat water to convert it into steam, to drive the turbines that generate electricity. For efficient functioning of the steam turbines, the steam is condensed into water after it leaves the turbines. This condensation is done by taking water from a water body to absorb the heat.
This heated water, which is at least 150C higher than the normal is discharged back into the water body. The warm water not only decreases the solubility of oxygen but changes the breeding cycles of various aquatic organisms. Oil is washed into surface water in runoff from roads and parking lots which also pollutes groundwater.
Groundwater pollution: While oil spills are highly visible and often get a lot of media attention, a much greater threat to human life comes from our groundwater being polluted which is used for drinking and irrigation. While groundwater is easy to deplete and pollute it gets renewed very slowly and hence must be used judiciously.
Groundwater flows are slow and not turbulent hence the contaminants are not effectively diluted and dispersed as compared to surface water. Moreover, pumping groundwater and treating it is very slow and costly. Hence it is extremely essential to prevent the pollution of groundwater in the first place.
Types of Groundwater Contamination: Groundwater pollution caused by human activities usually falls into one of two categories: point source pollution and nonpoint source pollution.
Point-source pollution refers to contamination originating from a single tank, disposal site, or facility. Industrial waste disposal sites, accidental spills, leaking gasoline storage tanks, and dumps or landfills are examples of point sources.
Chemicals used in agriculture, such as fertilizers, pesticides, and herbicides are examples of nonpoint-source pollution because they are spread out across wide areas. Similarly, runoff from urban areas is a nonpoint source of pollution.
Because nonpoint-source substances are used over large areas, they collectively can have a larger impact on the general quality of water in an aquifer than do point sources, particularly when these chemicals are used in areas that overlie aquifers that are vulnerable to pollution.
Water quality issues: The Water Quality Assessment Authority (WQAA) was constituted by the Central Government to exercise powers of the Environment (Protection) Act, 1986 for issuing directions and for taking measures to standardize method(s) for water quality monitoring and to ensure quality of data generation for utilization thereof and certain other purposes. Main issues with water quality are:
Ground water and Surface water interactions: Groundwater and surface water are essentially one resource, physically connected by the hydrologic cycle. Although water law and water policy often consider groundwater and surface water as separate resources, groundwater and surface water are functionally inter-dependent. Groundwater and surface water interactions are controlled by their hydraulic connection.
Hydraulically Connected Systems: If the groundwater table is in physical contact with the stream bed, it is a hydraulically “connected” system. The exchange of water between the groundwater system and a stream is controlled by the difference in elevation between groundwater table and the water level in the stream.
Hydraulically disconnected streams: If a stream is separated from the groundwater table by an unsaturated zone, it is a hydraulically “disconnected” system. In disconnected systems, although groundwater pumping does not affect streams, streams do affect groundwater through streambed seepage that recharges the groundwater system.
Legislations, policies and programmes for water pollution in India
The Indian Parliament drew immense inspiration from the proclamation adopted by the United Nations Conference on the Human Environment, which took place at Stockholm, 1972 and enacted the Water (Prevention and Control of Pollution) Act, 1974.
Salient features of Water Act:
Water act came into effect in 1974 to prevent pollution of water by industrial, agricultural and household water.
‘Water’ being a ‘state subject’, the Parliament can exercise the power to legislate on “water” only under Articles 249 and 252 of the Constitution of India. Accordingly, the Parliament enacted the Water (Prevention and Control of Pollution) Act, 1974. The Water Act represents one of the India’s first attempts to deal with an environmental issue comprehensively. The main features of this act are listed below:
Under Water Act, 1974, pollution control boards were created, who are responsible for implementation of its provisions. One of the important provisions of the Water Act, 1974 is to maintain and restore the ‘wholesomeness’ of aquatic resources. On national and state levels, there are several policies and regulation like Water (Prevention and Control of Pollution) Act, 1974 to regulate pollution discharges and restore water quality of our aquatic resources including the prescription of monitoring activities.
- Overall planning for the control of pollution on part of MoEF and the States falls short of an ideal situation. This would have repercussions on implementation of programmes for control of pollution and their outcomes.
- MoEF has not framed any legislation which specifically identifies pollution as an environmental offence and restoration of water bodies as a priority action.
- In the absence of an inventory for rivers and lakes, MoEF would not have adequate knowledge and information on the water resources for setting objectives for water pollution prevention and control and implementing responses to it.
- Absence of inventory of water bodies and keystone species associated with them leads to an incomplete understanding of water quantity and quality. The absence of such a database weakens the process of planning comprehensive and effective pollution control programmes.
- No studies have been carried out by MoEF/CPCB to probe the effects of industrial activities like paper mills, pharmaceutical industry, chemical plants, distilleries, tanneries, oil refineries, sugar factories and mining.
- MoEF/CPCB have set no water quality goals for the country. NRCD projects deal only with stretches where pollution has already occurred.
- Neither MoEF nor the States have introduced any programmes to prevent pollution of ground water. They have also not addressed the concerns of pollution from agricultural sources.
- A formal, periodic high-level review of implementation of the different elements of the National Environment Policy is essential at least once a year.
- While the outputs of the actions of CPCB and SPCBs are co-related, there is no functional co-relation between them at the input stage. There is no single agency to take charge of the issue of control of water pollution on a nation-wide basis.
- MoEF/CPCB should initiate steps, along with other client ministries like Ministry of Water Resources and all the States to draw up a comprehensive inventory of all rivers, lakes and ground water sources in India.
- It should also undertake a survey to list all the keystone species associated with each river and lake in India. This inventory should also be placed in the public domain
- MoEF/CPCB and most States need to intensify their efforts in developing biological indicators to ensure that the functional integrity of aquatic ecosystems are safeguarded.
- MoEF and most of the States need to also take steps to identify and quantify the effect that human activities like industries, agriculture, mining, urbanisation etc., have on water quality of rivers, lakes and ground water.
- MoEF can also coordinate with Ministry of Health and Family Welfare in assessment of risks to health posed by polluted water and get diseases caused by water pollution included in the Health Status Indicators published by the Ministry of Health and Family Welfare.
- MoEF should take into account the basin approach while planning for reduction of pollution of all rivers and lakes in the country. The basin approach will allow it to address the pollution of rivers and lakes holistically and integrate policies and plans with other ministries and civil society/research organisation.
- Establish enforceable water quality standards for rivers, lakes and ground water that would help protect human and ecosystem health. Penalties need to be levied for violations of water quality standards.
- Enhance capacities for spatial planning among the State and Local Governments, with adequate participation by local communities, to ensure clustering of polluting industries to facilitate setting up of common effluent treatment plants, to be operated on cost recovery basis.
- Minimum flow should be ensured in the perennial streams for maintaining ecology and social considerations.
- As maintenance of water resource schemes is under non-plan budget, it is generally being neglected. The institutional arrangements should be such that this vital aspect is given importance equal or even more than that of new constructions.
- The Water Quality Assessment Authority at the central level and the Water Quality Review Committee at the level of the States should be revitalized and strengthened so that it can act as a cross-sectoral nodal body for water pollution issues.
- MoEF should also start real time monitoring so that red flags are raised immediately when pollution levels rise alarmingly and remedial action can be taken in time.
- There is a need to augment financial resources either by improving effectiveness in realization of cess, increasing the rate of Water Cess or exploring other sources of revenue for control of water pollution.