(Adds details) VANCOUVER, British Columbia, Aug 3 (Reuters) - Canadian National Railway <CNR.TO> has been charged over a 2005 derailment that poisoned a scenic river near Vancouver, a railway spokesman said on Friday. CN Rail is still reviewing the two federal and three provincial charges that were filed against it on Thursday over the accident in the Cheakamus River canyon that killed an estimated 500,000 fish, spokesman Jim Feeny said. Nine cars of a 144-car CN train jumped the tracks on Aug 5, 2005, with one spilling caustic soda into the water. A Transportation Safety Board report last month said human error, poor supervision and CN's use of long trains to reduce operating costs all contributed to the accident on one of North America's most difficult mountain rail lines. The board's report slammed Canada's largest railway, saying it had failed to retain adequate "local knowledge" in operating the rail line that it had acquired in the 2004 purchase of BC Rail from the provincial government. The charges of violating British Columbia's Environmental Act carry fines of up to C$1 million ($946,000) each, while charges involving the federal Fisheries Act carry fines of up to C$300,000, officials have said in the past. Environmental officials raided three of the railway's offices in April as part of the investigation. CN has already spent an unspecified amount of money on efforts to restore the river's fish population. "We believe that we are making significant progress," Feeny said. ($1=$1.06 Canadian)
