U.S. congressional investigators said oil and natural-gas companies have injected more than 122 million liters of fluids containing diesel fuel in a widely used technique known as hydraulic fracturing. Democratic lawmakers said the practice by big companies appears to violate U.S. laws on safe drinking water because the companies did not obtain necessary permits for the use of diesel fuel. However, the investigation by Representative Henry Waxman (Democrat from California) found no evidence that the practice contaminated water supplies. The investigation found that 12 of 14 companies hired to perform hydraulic fracturing used diesel alone or in a mixture from 2005 to 2009. Of the 122 million liters reported, most was injected in Texas, followed by Oklahoma, North Dakota, Louisiana, and Wyoming.
