Divers were at the Ballard Locks on Thursday and shot underwater video.
Environmentalists say coal is falling from trains as they pass overhead on the railroad trestle. About two trains pass each day now, but that will increase to 10 or more if those export terminals are built.
The issue over coal dust falling onto the side of the tracks is not new. But this is the first time coal has been found in the delicate marine ecosystems.
Divers for Puget Soundkeepers Alliance say it is easy to find coal in the marine waters.
They believe it has been falling off trains as they rumble overhead, a couple of times a day, between Wyoming and Canada.
But underwater videos show - if it's this easy to find coal now, imagine if five times as many of these coal trains, each a mile and a half long, rumbling through Washington state and Seattle every day enroute to proposed coal export terminals in Bellingham and elsewhere on the coast.
Divers have searched sites from Seattle to Everett.
"And we've found coal at every site where we've looked," says Chris Wilke of Puget Soundkeepers Alliance.
On Thursday, it took divers only a few minutes to find chunks of coal.
Previous samples have come from Carkeek Park, Burke Gilman Trail and elsewhere. All are being tested in a lab to make sure it's coal.
Photos from the Columbia River show what the Sierra Club is certain is coal - they had it tested and showed KOMO News the lab results.
The coal industry says they'll put what they call a surfactant on the top of all the coal trains, reducing the amount of coal that comes off of them during transit by 85 percent.
But critics says it still means millions of pounds of toxic coal, which will fall into Puget Sound and spread underwater.
From there they say it can break down into smaller pieces more readily. And it can enter the food chain more readily.
The coal industry is skeptical, to be sure, saying there are a lot of independent reviews out there and this is not one of them.
Government regulators haven't even launched environmental impact studies yet on proposed coal terminals.
Still, critics may have more to say next week when lab results come back on those samples taken from the area of the Ballard Locks.