( 1 ) THIS petition - public interest - under Article 32 of the Constitution of India was initially directed against the tanneries located in the city of Kanpur. This court by the order dated 22/9/1987 (M. C. Mehta v. Union of India) (Kanpur tanneries) issued various directions in relation to the Kanpur tanneries. While monitoring the said directions, the scope of the petition was enlarged and the industries located in various cities on the banks of River Ganga were called upon to stop discharging untreated effluent into the river. In this judgment we are concerned with the tanneries located at Tangra, Tiljala, Topsia and Pagia Danga the four adjoining areas in the eastern fringe of the city of Calcutta (the Calcutta tanneries ). These areas accommodate about 550 tanneries. According to the examination report dated 30/9/1995 by the National Environmental Engineering Research Institute (NEERI), ninety per cent of the Calcutta tanneries use chrome- based tanning process, while the remaining utilise vegetable tanning process. The present status of the four tannery clusters in Calcutta, according to the NEERI Report, is as under:

"it was observed by the inspection team that no appropriate waste water drainage and collection systems are available in any of the tannery clusters. The untreated waste water flows through open drains causing serious environmental, health and hygiene problems. Also, no waste water treatment facilities exist in any of the four tannery clusters. "the observations by the NEERI team, regarding the Calcutta tanneries in the report are as under:

"tannery units are located in highly congested habitations, offering little or no scope for future expansion, modernisation or installation of ETP (s ).

TANNERY units are located in thickly populated residential areas.

SURROUNDINGS of the tanneries are extremely unhygienic due to discharge of untreated effluents in open drains, stagnation of wastewater in low-lying areas around the tannery units, and accumulation of solid waste in tanneries. "it is thus obvious that the Calcutta tanneries have all along been operating in extreme unhygienic conditions and are discharging highly toxic effluents all over the areas. This court on the basis of the material on the record in Kanpur tanneries order observed as under regarding the noxious nature of the tannery effluent:

"it should be remembered that the effluent discharged from a tannery is ten times more noxious when compared with the domestic sewage water which flows into the river from any urban area on its banks. "needless to say that the State of West Bengal and the West Bengal Pollution Control Board (the Board) are wholly remiss in the performance of their statutory obligations to control pollution and stop environmental degradation.

( 2 ) ON 19-2-1993 the State government informed this court that the Calcutta tanneries were being shifted from their present location and the new location would be fully equipped with pollution control devices. This court gave three months time to the State government to take appropriate steps in that direction. The State government by way of an application sought extension of time for the shifting of the Calcutta tanneries. This court considered the application on 13/8/1993 and passed the following order:

"the State of West Bengal has moved an application for extension of time for the shifting of over 500 tanneries functioning on the bank of River Ganges. This court by its order dated 19/02/1993 gave three months time to the State of West Bengal to take appropriate steps. The relevant part of the order is as under:

as regard the industries in Group d Part II of Annx. a, the State government is said to be taking steps for shifting these industries from the place where they are presently located to another place and to erect a common effluent plant for them in the new place. In that view of the matter, the State of West Bengal shall take appropriate steps within a period of three months. we see n