A U.S. study of hydraulic fracturing,...using blasts of water and chemicals to free natural gas from shale rock, triggered clashes between New York state supporters and opponents of the technique. The Environmental Protection Agency should limit its study..., gas-industry representatives and some local officials said at an agency hearing yesterday... Opponents backed the agency’s plans for a broader review... No direct links have been found between groundwater contamination and hydraulic fracturing in New York, said Brad Gill, executive director of the...Independent Oil & Gas Association of New York, an industry group whose directors include representatives from Halliburton Co., which produces fracturing fluids, and Talisman Energy Inc... Last month, the EPA told residents of Pavillion, Wyoming, not to drink water after benzene, methane and metals were found in groundwater...EnCana Corp. is the primary gas operator in the area... [also refers to Chesapeake Energy]