Assam's Pollution Control Board found the oil industry had for over four decades been destroying resource-rich areas through deforestation and preventing tree regeneration by not cleaning up spillages. Pollution control officials also found that oil companies were contaminating groundwater by dumping sludge in ponds and polluting a major river by discharging untreated effluents, posing health risks to millions of people...Assam produces about 15 percent of India's onshore crude -- with state-owned exploration companies, Oil India Limited and Oil and Natural Gas Corporation Limited supplying crude oil to state-run Indian Oil Corporation's refineries...Oil industry officials admit that they have been responsible for some of the damage but say they are trying to clean up pits and are also modernising to stop hurting the environment.