BNSF Railway Co. is polluting Washington’s waterways with releases of coal dust and chunks of coal from open-top rail cars, a lawsuit filed Wednesday alleges.

The Spokane Riverkeeper joined the Sierra Club, Puget Soundkeeper Alliance and other nonprofit groups in filing the suit in U.S. District Court in Spokane. A companion lawsuit was filed in Western Washington.

The lawsuit names the Spokane River and its Hangman Creek tributary among Eastern Washington waterways affected by coal releases, which the suit says is a violation of the federal Clean Water Act.

The Spokane Riverkeeper’s Bart Mihailovich said he and volunteers collected pebble-size chunks of coal from the river and Hangman Creek near three railroad crossings last spring. A lab analysis confirmed that the material was coal, he said.

Coal transport represents about $4.8 billion in freight revenue for BNSF annually, with most of the coal originating in Wyoming and Montana’s Powder River Basin, according to the lawsuit. The number of coal trains in the Northwest would increase dramatically if three proposed coal export terminals are built in Oregon and Washington.

Gus Melonas, a BNSF spokesman in Seattle, said he couldn’t comment on the litigation.

However, he said the coal is packed into railcars in a loaf shape and sprayed with a glue to reduce releases. Up to 2 inches of the glue is applied. “It’s found to be effective,” Melonas said.