Not sure about the ones in Montana but I just ran through the inspection station this weekend coming back from Cascade, MT. I know a bunch of people doing the inspections and they will be set up at Coutts, Crowsnest Pass, Dunmore, Oyen, and a bunch of other sites. They are looking for anything invasive with the main concern on Zebra and Quagga Mussels as well as Eurasian Water Milfoil.
Basically make sure you wash your boat well between water bodies and drain anywhere that might hold water. I wasn't aware that it was mandatory to get inspected in Montana before dropping into the water and the US border guys said nothing about it.