( 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 appropria