National Water Quality Monitoring at a Glance
The Central Pollution Control Board (CPCB) has established a network of monitoring stations on rivers across the country. The present network is comprising of 870 stations in 26 States and 5 Union Territories spread over the country. The monitoring is done on monthly or quarterly basis in surface waters and on half yearly basis in case of ground water. The monitoring network covers 189 Rivers, 51 Lakes, 4 Tanks, 2 Ponds, 3 Creeks, 4 Canals, 10 Drains and 218 Wells. Among the 870 stations, 566 are on rivers, 55 on lakes, 10 on drains, 12 on canals, 4 on tank, 3 on creeks and 2 on pond and 218 are groundwater stations. The monitoring of water quality at 256 stations is being done on monthly basis, 392 stations on quarterly basis, 218 on half yearly basis and 4 stations on yearly basis. Presently the inland water quality-monitoring network is operated under a three-tier programme i.e. GEMS, Monitoring of Indian National Aquatic Resources System and Yamuna Action Plan. Water samples are being analysed for 28 parameters consisting of physico-chemical and bacteriological parameters for ambient water samples apart from the field observations. Besides this, 9 trace metals and 15 pesticides are analysed in selected samples. Biomonitoring is also carried out on specific locations. In view of limited resources, limited numbers of organic pollution related parameters are chosen for frequent monitoring i.e. monthly or quarterly and major cations, anions, other inorganic ions and micro pollutants (Toxic Metals & POPs) are analysed once in a year to keep a track of water quality over large period of time. The water quality data are reported in Water Quality Status Year Book.
The water quality data on all the monitoring locations is computed for the year 2004 and is summarized as minimum, maximum and mean value for all the rivers in a basin. The monitoring locations are arranged according to the longitudinal profile of the river from its origion to its confluence with the deeper valley of the larger river or before meeting to the sea. Basinwise summarized data may be accessed through below given links. The monitoring locations on canals, creeks and drains; lakes, ponds and tanks; and groundwater aquifers are listed out alphabetically for States and Union Territories.
Objective of Water Quality Monitoring
The Central and State Pollution Control Boards / Pollution Control Committees in Union-Territories in India are responsible for restoration and maintenance of the wholesomeness of aquatic resources. To ensure that the water quality is being maintained or restored at desired level it is important that the pollution control boards regularly monitor the water quality. The water quality monitoring is performed with following main objectives in mind:
· For rational planning of pollution control strategies and their prioritisation;
· To assess nature and extent of pollution control needed in different water bodies or their part;
· To evaluate effectiveness of pollution control measures already is existence;
· To evaluate water quality trend over a period of time;
· To assess assimilative capacity of a water body thereby reducing cost on pollution control;
· To understand the environmental fate of different pollutants.
· To assess the fitness of water for different uses.
Present Approach to Water Quality Management
The water quality management in India is performed under the provision of Water (Prevention and Control of Pollution) Act, 1974. The basic objective of this Act is to maintain and restore the wholesomeness of national aquatic resources by prevention and control of pollution. The Act does not define the level of wholesomeness to be maintained or restored in different water bodies of the country. The Central Pollution Control Board (CPCB) has tried to define the wholesomeness in terms of protection of human uses, and thus, taken human uses of water as base for identification of water quality objectives for different water bodies in the country. It was considered ambitious to maintain or restore all natural water bodies at pristine level. Planning pollution control activities to attain such a goal is bound to be deterrent to developmental activities and cost prohibitive. Since the natural water bodies have got to be used for various competing as well as conflicting demands, the objective is aimed at restoring and/or maintaining natural water bodies or their parts to such a quality as needed for their best uses. Thus, a concept of designated best use (DBU) was developed. According to this concept, out of several uses a water body is put to, the use which demands highest quality of water is termed as designated best use, and accordingly the water body is designated. Primary water quality criteria for different uses have been identified. A summary of the use based classification system is presented in table 1.
Table 1 : Use based classification of surface waters in India