Tuesday NBC Montana spent the day digging into a city council demand to study the environmental impact of coal shipments through Missoula.  

The state’s coal is mostly mined in southeastern Montana and then loaded onto rail cars and shipped directly to Washington state through Missoula.

Now a new proposed port facility may be built in Washington, meaning more coal would be shipped through Montana.

The proposed port, called the Millennium Bulk Terminal, would be built on the Columbia River near Longview, Washington, roughly 517 miles from Missoula and about an hour-and-a-half inland from the Pacific coast.  

According to some activists, Missoula would feel the impact of unit trains passing through and that's why they're pushing the Army Corps of Engineers to add Missoula to its study on environmental impacts.

Missoula is no stranger to coal shipments -- some say it creates jobs and state revenue while others argue the impacts shipping and burning coal are too much to ignore.

Don Hyndman, a retired University of Montana geology professor, says he wants an impact study done in hopes the results would stall or block the construction of the proposed port in Washington state.   

“If you mine coal you know what the final consequence is going to be,” says Hyndman.  “It's going to be burned somewhere because people aren't going to mine it and not use it.”

Hyndman says he's worried increased coal shipping would create more statewide train traffic and overall hurt the environment.

“You burn coal, you generate carbon dioxide and that carbon dioxide is a greenhouse gas,” he explains.  “It heats up the earth’s atmosphere and it prevents very much of that heat from getting back through the atmosphere and into outer space.”

NBC Montana identified 12 coal mines in the state and, according to the Montana Coal Council, in 2012 Montana produced 36.7 million tons of coal.

Shipping port proponents say increased coal shipping creates much needed jobs and state tax revenue.

Shelby DeMars, a regional representative for Count on Coal Montana, says the passage of a resolution asking for Missoula to be included in the impact study just delays any benefits coal can bring the state.

“We stand to gain so much as a state economically because of the resources that we can then export and get more Montana products to market, but also just the economic activity and the jobs that it would create,” DeMars says.   “The greatest threat is not the construction of the terminals but the potential for those terminals not to be constructed.”

NBC Montana learned Helena city officials have also voiced concern over increased coal shipping and at least 13 cities in the northwest have asked to be included in the impact study.

Representatives with the Army Corps of Engineers tell us they are accepting public feedback on the proposed Millennium Bulk Terminal until November 18.

If you want to share your thoughts on the proposed shipping terminal with the Army Corps of Engineers, click here.