On Friday, a magnitude 7.5 earthquake happened near Hebgen Dam in southern Montana - but it wasn't real. It was part of Vigilant Guard, a state-wide training exercise.
Over the last few days, the exercise has simulated dam failures leading all the way up to Great Falls.
Authorities started planning for the flood waters to make their way to Great Falls.
"With this particular thing, we are in support of Vigilant Guard, which is the exercise for the guard, we are playing that role for them as the local jurisdiction,” said Steven Hester, Emergency Operations Center Commander.
On Monday, the emergency operations center and a joint information center were set up help support the emergency response within Great Falls.
"That water reached Great Falls and now the city is cut into two. It is completely impossible to reach from one side of Great Falls to the other. As you can imagine, lots of issues would result from something like that,” Captain Ryan Finnegan, Montana National Guard Public Affairs, said.
“In this scenario, half of our resources are gone. We have to improvise, we have to adapt, and we have to figure out how to make things happen without the capabilities that you are used to,” Lieutenant Colonel Glen Heaton, a flight surgeon with the Montana Air National Guard, said.
On the other side of town, military members from the Montana and Oregon National Guard as well as Malmstrom Air Force Base have set up a triage area for a chemical spill at the Westgate Mall.
"We will bring them up to the hill and they will actually get on a C-17 or a C-130 and they will be going to Billings, Kalispell, and Missoula. They will be delivered in an attempt to overwhelm them as well,” Heaton said.
But the goal of this exercise is to make sure the plans that are put in place will keep Montanans safe if something like this does happen in the future.
Vigilant Guard will wrap up Wednesday afternoon.