The heavy mountain snowfall in southwestern Montana this spring has officials forecasting floods in many of the rivers in the area.
Of particular concern is the lower Big Hole River in western Madison County, said Gina Loss, hydrologist with the National Weather Service in Great Falls.
The weather service has issued a flood watch for the lower Big Hole River near Melrose. The river in that area is predicted to hit flood stage by Thursday morning.
Loss spoke to government officials and other citizens on a conference call Monday. The situation she outlined compares to historical snowpacks and spring floods like 1975 and 1997.
Snowpack in both the Jefferson and Madison River basins is well above normal, Loss said. Snowpack in the Jefferson River basin is 152 percent of normal and in the Madison it’s 144 percent of normal.
This is due largely to the delay of spring run-off conditions, she said. Typically, streams are already swelling with run-off and snow amounts in the mountains have peaked. However, this year cooler temperatures and late spring storms have kept snow in the mountains and run-off at bay.
The problem is this scenario won’t last forever, and the longer run-off waits to get started, the more likely it is the snow will melt over a shorter time frame and cause flooding issues, Loss said.
“Pretty much the entire state has more water than they know what to do with,” she said. “We are getting late enough now that if we don’t start warming up at least a little bit, it’s just going to make it more painful when it does.”
Loss also predicts the Big Hole River near Melrose has a 98 percent chance of having a major flood event sometime this spring.
Julie Meyer with the weather service explained the prediction as a result of several factors, including snowpack and historic temperature patterns. Essentially, with normal weather conditions from now on through the spring, the lower Big Hole could be above flood stage from the end of this week into the middle of June, Meyer said.
In response to the flood watch, Madison County officials have begun to gather resources in the area, said Steve DiGiovanna, communications coordinator for Madison County.
“We’re going to put together a little more proactive take on this weather situation and the river problem,” DiGiovanna said.
He is recommending that people living near the lower Big Hole and Jefferson River be watchful of river levels and have a plan together for what to do if flooding starts.
“The first thing is to have a plan and be ready to act on that plan if the water starts rising,” DiGiovanna said.
Flooding on the lower Big Hole is a common occurrence and most of the time doesn’t do much damage. However, this year could be a unique event with much higher water levels. Flood stage on the lower Big Hole is about six feet; major flooding is eight feet – level the river is highly likely to reach this year, Loss said.
Along with the melting snowpack, May and June are also wet months in southwest Montana, she said. People should expect rain, which will also add to already high river flows.
The county will have information about sandbags and river levels along with any emergency warnings or actions that are underway, DiGiovanna said. He encouraged people to check the Madison County emergency management website at madison.homestead.com or call 843-5243.
Even if you’re not near the Big Hole, Loss still wants people to be vigilant of river levels.
“Right now I would expect higher river runs this year,” she said. “My gut feeling is we’re going to have high rivers all across Montana this spring.”