Missoula moved from a flood watch to a warning at 6 p.m. Thursday, with waters rising in some Orchard Home areas.
The Clark Fork River reached 8.3 feet at 4 p.m. Thursday, pushing it above the minor flood stage of 7.5 feet. It’s expected to crest at 9.7 feet Saturday evening, then start a downward trend into next week.
“We’ve officially entered the flood season,” said Adriane Beck, director of Missoula County’s Office of Emergency Management. “Actually, this is the second time this year we’ve entered in the minor flood stage on the Clark Fork River.”
The river is considered to reach the minor flood stage at 7 feet, with flows around 1,200 cubic feet per second. Moderate flood stage is 11 feet, with flows of 22,400 cfs, and major flood stage, which was topped last year, is 13 feet, or 29,400 cfs.
A flood advisory first was issued this year on April 23, when the river reached 7.5 feet. After last year’s flooding, the minor flood stage dropped from 10 feet due to the impacts that were seen at the minor flood stage level.
Ray Nickless, a hydrologist with the National Weather Service, said the rise in flows has to do with the warm weather in recent days melting the mountain snowpack. Rain is expected to add to the flows beginning Friday.
“The good news, from the standpoint of the river, is the forecast is for cool air that will shut down the snow melting progress,” Nickless said. “Of course we’d like to see a little nicer weather, but the cool temperatures will make the river slowly recede as we get into next week.”
High temperatures are expected to be in the upper 50s to low 60s throughout the weekend, with overnight lows in the 40s. Nickless expects snow in the mountains, with anywhere from a half-inch to three-quarters of an inch of rain on Friday and lighter rains Saturday and Sunday.
The Bitterroot River is expected to crest at 10.5 feet late Saturday afternoon, which is about half a foot below its minor flood stage.
“It’s getting up there, but you won’t see a lot of impacts,” Nickless said. “You get water in the area just past the Lolo, where the buffalo hang out, and at the Linda Vista Golf Course. But nothing like we see with the Clark Fork, where the river starts rolling through the streets."
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Beck said they’re seeing some flooding in the Kehrwald Drive area and the Tower Street open space area. Last year’s flooding created new channels that the Clark Fork flows through when the water levels are high. Other residents in the area could be affected by rising groundwater levels.
However, Beck doesn’t anticipate any evacuations at this point.
“We always put a lot of thought and consideration as to why evacuations might be needed. It’s always based on public safety, and if the need is there we’ll consider it then,” Beck said. “But we don’t have to do that right now.”
Still, she encourages all residents to sign up for Smart911 at smart911.com or download the app, which allows her office to alert residents of immediate safety concerns in their neighborhoods. This includes any evacuation notices.
Beck adds that free sandbags and sand are available at Fort Missoula, and urges citizens at risk of flooding to use them to protect their properties. Her office recommends constructing a circular — not square — perimeter around the foundation. An online Army Corps of Engineers video shows filling techniques and placement methods at https://youtu.be/-hQPAlFMVtM.
Missoula County has an emergency proclamation in place in preparation for any flooding, which allows Beck's office to pull in other agencies that have a role to play when floods occur.
She urges people to stay out of the floodwater, since it can be contaminated by septic systems and include bacteria and viruses that can cause infection and illness. People floating on area rivers also need to watch for debris, but most of the larger items — like entire trees and mobile homes from the river banks — probably already were disturbed last year.
“Just pay attention. With the warming temperatures and rain in the forecast, we’ll see all the rivers rise and some of the small streams, which tend to react a lot more quickly and violently than on the larger rivers,” Beck said. “There’s debris, milky water where you can’t see what’s below, and the stream banks are a little stressed.”