Indian Oil Corporation's Guwahati Refinery has been served a show-cause notice by the Pollution Control Board, Assam (PCBA) for failing to meet a deadline fixed by the latter to stop polluting the Brahmaputra. PCBA chairman JL Dutta said the IOC refinery had already caused "serious harm' to the Brahmaputra river. "You cannot allow the Brahmputra to go the Ganga way,' he said. "While the acceptable level of phenolic compounds is just one milligram per litre, the refinery's effluents released to the Brahmaputra contain over 18 mg per litre. Levels of total suspended solids, sulphide and oil and grease are also very high,' Dutta said. The PCBA had last year written to the four refineries in the state to bring down their effluent discharge level to zero within October. "But, despite our repeated letters, Refinery has miserably failed to meet the new stipulations,' the PCBA chairman said.