Winter Flood Season – It Is Approaching

Gallatin County Emergency Management


Gallatin Gateway - 2014

Gallatin Gateway – 2014

As we move farther into winter our historical winter flood season is approaching.  Winter flooding in Gallatin County is typically caused by freezing of the rivers and ice dams forming.  When we see sustained sub zero cold we often have rivers (and other waterways) that begin to freeze up.  When ice forms in these waterways the ice takes up the space that the water used to occupy which forces the water up.  As this cycle continues with more ice forming under the water, the water level rises.  In other situations a obstruction occurs forming an ice jam.  In this situation, it causes the water to slow forming more ice and the water backs up behind the ice jam (like a lake).  This also causes the water level to rise and also presents a down stream risk if the ice jam suddenly releases everything trapped behind it.

The questions for residents in Gallatin County is if you have a waterway near your house, have you ever seen it flood in the winter?  If you have, it is recommended that you develop a plan on what you will do to protect your property if you observe it beginning to flood this winter.  Fighting a flood is an offensive sport.  Once flooding has occurred and affected your property, it is often too late to prevent the damage.  The best strategy is to have a plan on what you will do, identify where you will get the needed supplies, and closely monitor the waterway.  If you see flooding begin, you should implement your plan before you are flooded.  More on flooding at

It is also important for winter river recreationalists to be alert while when on the river.  If you have heard about an ice jam being present on a river, recreate someplace other than below the ice jam.  Even if you haven’t heard of an ice jam being in place, that doesn’t mean there isn’t one.  Be alert to your surroundings, pay attention to strange sounds or sudden changes in water level, and if in doubt – get out of the river.  Several years ago Search and Rescue had to rescue a winter fisherman from the Gallatin River when an ice jam let loose.  The fisherman had walked out to a gravel bar where he was fishing when the ice jam released.  He was quickly surrounded by water and trapped on what had become an island due to the river water flow that was now released.