Several conservation groups plan to sue Burlington Northern Santa Fe Railway and top U.S. coal producers, claiming they discharge coal into Washington state waterways in violation of federal law.

The groups allege the companies discharge coal, coal chunks, coal dust and other pollutants into state waters from rail cars that transport Rocky Mountain coal throughout Washington.  The Sierra Club, Puget Soundkeeper Alliance, Columbia Riverkeeper and other groups on Tuesday notified BNSF, Arch Coal, Peabody Energy, Cloud Peak Energy and others of their plan to bring a citizen lawsuit under the federal Clean Water Act.

The group says the train and rail cars are point sources of pollution, and that the companies should have gotten a permit for the discharges. Meanwhile, The last partner has dropped out of a proposal to ship coal from Montana and Wyoming to Asia through the Port of Coos Bay in Oregon.

The port issued a statement Monday saying Metropolitan Stevedore Company of Wilmington, Calif., known as Metro Ports, did not renew the exclusive negotiating agreement that expired Sunday. Two other partners dropped out earlier.

Port CEO David Koch said the port is continuing to develop new shipping facilities, but did not say if that would include coal.  Four other Northwest ports are still working on coal shipping proposals.