Mystery shrouds contamination of the abandoned stone quarry at the Cuncolim Industrial Estate with the authorities unable to identify the source and the units responsible for discharging untreated effluents into it. While sample testing of the water by the Goa State Pollution Control Board (GSPCB) has revealed high Biological Oxygen Demand and Chemical Oxygen Demand, besides the presence of manganese and iron, even as the source of contamination is yet to be traced. The effluent treatment plants of the two food processing units adjacent to the quarry have been found to be functioning satisfactorily, throwing up questions over the units responsible for the discharge of the effluents into the water body. GSPCB Chairman Jose Manuel Noronha said that the Board was keeping a close track of activities of the food processing industries, including the fish meal plant in the estate. “It’s true that the water samples from the stone quarry showed very high BOD and COD, indicating that effluents have found its way into the quarry. However, the ETPs of the two units close to the quarry were found to be in order,” Noronha said. He, however, said that the GSPCB is maintaining a close watch on the activities of the food processing units in the Cuncolim Industrial estate. “The Board has already told these units to deposit Rs one lakh bank guarantee, which will be forfeited if they are found violating pollution control norms. We have given them four weeks to put things in place before surprise inspections begin,” Noronha added. While the GSPCB says it is keeping a tab on the activities of the units, the mystery behind the discharge of the untreated effluents into the quarry still remains unresolved. Added to the problem is the admission by GSPCB officials that it’s not possible to monitor and physically verify the activities of each and every unit.