» Under the Indo-Dutch collaborative project, the development of bio-monitoring methodology for Indian river water quality evaluation was initiated during 1988. The Central Pollution Control Board carried out a pilot study on the River Yamuna for a selected stretch from Delhi upstream to Etawah downstream. The main objective of this study was to formulate strategic methods, which can be accepted in scientific and legislative framework for water quality evaluation. The application of methodology was undertaken for water quality evaluation of River Tungbhadra, River Chaliyar and the Damodar River.

» Subsequently, it was decided in the 42nd Chairmen and Member Secretaries conference of Pollution Control Boards that the inclusion of biological parameters in the monitoring network of MINARS will enhance the quality evaluation in a cost effective manner. The State Pollution Control Boards were advised to ensure that all the natural aquatic resources should meet the desired quality criteria in terms of physico-chemical and biological parameters.

» Since then, CPCB has been exploring the possibilities to introduce bio-monitoring methodology for water quality evaluation of surface water bodies.

» The nationwide bio-monitoring programme has been strengthened through following projects undertaken during past few years in collaboration with State Pollution Control Boards, Pollution Control Committees, NGOs, Local authorities and various research organizations.

a) Water quality assessment of raw water intake for drinking water supply, utilizing artificial substratum for bio-assessment of water bodies.
b) Bio-mapping of Rivers
c) Bio-monitoring of surface water bodies existing in problem areas.
d) The nationwide project on 'Water quality assessment through bio-monitoring of wetlands in the wild life habitats in India' has been initiated by Central Pollution Control Board and as such the State Boards were requested to identify wetlands/ surface fresh water bodies existing in major wild life habitats.

» To facilitate the nationwide monitoring network training programmes on "Bio-monitoring of Water Quality" had been organized for State Pollution Control Boards personnel from time to time, since past several years.

» To strengthen the State Pollution Control Board official on scientific background of the bio-monitoring methodology, on the job trainings were imparted through various on-going and collaborative projects on bio-monitoring.

» Central Pollution Control Board (CPCB) during development and validation of bio-monitoring methodology under the Indo-Dutch Bilateral Programme on bio-monitoring had established the fact that among all the biological components of the aquatic ecosystem, benthic macro-invertebrates are best suitable for biological evaluation of water quality.

» Most of these macro- invertebrates particularly insect larvae are aquatic and share their biological life in fresh water. Their adults fly over for miles together in search of suitable fresh water environment for reproduction, breeding and laying eggs for establishment of biological communities in suitable habitats.

» The biological water quality evaluation of water bodies has been undertaken using Biological Water Quality Criteria (BWQC) by Central Pollution Control Board (Table-1). The abnormal combination of range of saprobic score with diversity score indicates sudden change in environmental conditions. The water quality classes obtained from the biological water quality evaluation, may be interpreted in terms of designated best uses.

Table 1: Biological Water Quality Criteria (BWQC)