Teck has paid millions in fines related to pollution from its British Columbia operations and is still working to stem the contamination of watersheds in the region.
Legal action filed in Montana names Teck Coal Ltd. as a one of three defendants in a request for judicial review by environmental groups in Montana and Idaho.
Australia is the world's largest exporter of LNG, although it is likely to be overtaken by rivals the United States and Qatar as both those countries expand capacity at a faster pace.
Some Canadian institutional investors have lobbied the federal government to push the nation's biggest pension funds to lift their exposure to domestic companies.