By PHUONG LESEATTLE (AP) â¿¿ Several conservation groups on Tuesday announced plans to sue Burlington Northern Santa Fe Railway and several top U.S. coal producers, claiming they spill coal into Washington state waterways in violation of federal law. The Sierra Club and other groups allege the companies discharge coal, coal chunks, coal dust and other pollutants into state waters when Rocky Mountain coal carried in open-rail cars across the state get blown, shaken or fall off. Many of those rail lines run along rivers, lakes and streams, and the coal and other material end up in those waters, potentially harming aquatic life, ecosystems and people, according to the groups, which include Puget Soundkeeper Alliance, Columbia Riverkeepr, Friends of Columbia Gorge and RE Sources for Sustainable Communities. On Tuesday, they sent BNSF and Arch Coal, Peabody Energy, Cloud Peak Energy, Ambre Energy and other companies a 60-day notice of intent to sue, a step required before bringing a citizen lawsuit under the federal Clean Water Act. Responses from BNSF Railway and a Northwest trade group that includes the nation's top coal producers were not immediately available Tuesday. "Coal is a toxic pollutant," containing mercury, arsenic and other metals, said Brett VandenHeuvel, executive director of the Columbia Riverkeeper, during a call with reporters Tuesday. "So we're taking this action today to stop the spilling of pollution into our rivers." Coal is currently shipped to British Columbia on rail lines operated by BNSF where it's exported to Asia. Coal is also shipped to the state's only coal-fired power plant in Centralia, owned by TransAlta. Several top U.S. coal producers are now seeking to ship millions of tons of coal from the Powder River Basin of Montana and Wyoming for export to Asia. The U.S. Army Corps of Engineers is currently reviewing permits for three proposed shipping terminals, including one at Boardman, Ore., and two in Washington at Longview and Bellingham.