Mold After Flooding in Montana: What the 2022 Floods Taught Us
Montanans do not think of themselves as flood-prone, and most of the time they are right. But every few years the rivers remind us. In June 2022, record rain on a heavy snowpack sent the Yellowstone River through Park County, and the Gallatin River ran at roughly 8,930 cubic feet per second, near record levels. Spring snowmelt flooding was a valley-wide warning as recently as April 2018. Flooding does the obvious damage fast; mold does the slow damage afterward, and it starts in the first two days. This post covers what happened in 2022, why the clock matters, and what to do in the first hours and weeks. Our water damage and mold cleanup service handles exactly this situation.
What happened in the 2022 Yellowstone and Gallatin floods?
In mid-June 2022, warm rain fell on a late, deep mountain snowpack and the Yellowstone River rose to historic levels. In Park County alone, 205 residences were damaged: 3 destroyed, 76 with major damage, and the rest with lesser damage. Southeast Livingston was hit especially hard, and residents on Ninth Street Island had to be rescued. The federal government declared a major disaster, FEMA DR-4655, which opened individual assistance to affected homeowners. West of Bozeman Pass, the Gallatin River peaked at about 8,930 cfs, and low-lying properties near the river from Gallatin Gateway through Manhattan saw high water in crawl spaces and basements.
In the weeks that followed, the pattern in the damaged homes was familiar to anyone in our line of work. Houses that were opened up, gutted to the studs and dried within days came through well. Houses where the water sat, or where wet drywall and carpet were left in place while owners waited on insurance or contractors, grew mold on nearly every porous surface by the time anyone got to them.
Where is flooding a risk around Bozeman?
Three situations account for most flood-related mold calls in the Gallatin Valley.
River flooding. The Yellowstone at Livingston, the Gallatin from Big Sky down to Manhattan, the East Gallatin through Bozeman and Belgrade, and the Madison and Jefferson near Three Forks. Three Forks is the most exposed town in the region: roughly 80 percent of its structures sit in the regulatory floodplain, and a recent remapping placed a northern neighborhood in the floodway. A $5.5 million conveyance channel on the Jefferson, backed by a $4.2 million FEMA grant in 2024, is meant to reduce that risk, but the town's crawl spaces and basements remain vulnerable.
Spring snowmelt. Bozeman gets 86 to 91 inches of snow a year, and when it melts in March and April the ground is still frozen a few inches down. Water runs across the surface, pools against foundations and overwhelms window wells and sump pumps. The April 2018 warning covered the whole valley. This is the kind of flooding that shows up as an inch of water across a basement floor rather than a river in the living room, and it is far more common.
High groundwater. Four Corners sits on a shallow alluvial aquifer about 55 feet down, and parts of the valley floor see the water table rise close to the surface in early summer. Crawl spaces that are dry in September can be damp by June.
Why does the 24 to 48 hour window matter so much?
Mold spores are everywhere, all the time. They are harmless until they land on a wet, organic surface, and then they begin to grow within roughly 24 to 48 hours. Flood water soaks drywall, carpet pad, insulation, particleboard cabinets and the paper facing on everything, which is the ideal food. If those materials are dried, or removed, within two days, you have a water-damage job. If they sit for a week, you have a water-damage job and a mold job, and the second one is usually more expensive than the first. MSU Extension's guidance is direct: porous materials that have been wet for more than two days should be discarded.
After any flood or significant water intrusion, the goal for the first 48 hours is simple: get the water out, get the wet porous material out, and get air moving. Waiting for an adjuster to see the room before you start drying it is the single most expensive mistake homeowners make. Photograph everything thoroughly, then start.
What should I do in the first 48 hours?
Make it safe
Turn off electricity to flooded areas at the breaker if you can do so without standing in water. Treat river and groundwater flooding as contaminated; wear boots, gloves and an N95. Floodwater near agricultural land or septic systems may carry sewage.
Document
Photograph and video every room, the water line, and every damaged item before moving anything. Note the date and time. This is what your insurance claim or FEMA application will rest on.
Remove water and wet material
Pump or wet-vac standing water. Pull up carpet and pad, remove wet drywall at least a foot above the water line, and pull out wet insulation. Bag and remove soaked porous contents: upholstered furniture, mattresses, cardboard, paper.
Dry aggressively
Open windows if the outside air is dry, run fans and dehumidifiers, and open wall cavities and cabinet toe-kicks so air reaches the framing. Professional drying equipment and moisture meters shorten this from weeks to days.
What happens after the first week?
Once things are dry, the question becomes whether mold got established. Framing and subfloor should be checked with a moisture meter and inspected for staining. Any material that was wet for more than two days and could not be removed within that window should be treated as suspect. This is the point at which a professional inspection pays for itself, because it determines whether you need a cleaning and treatment job on the framing or a full remediation with containment. If mold has started, we isolate the area, run HEPA filtration, remove and clean contaminated material, and document everything for your insurer. A typical water-damage-plus-mold room in our area runs $2,000 to $6,000; see our cost page for the full range.
Does insurance or FEMA cover flood mold?
Standard homeowners insurance does not cover river or surface-water flooding at all; that requires a separate flood policy. It usually does cover sudden plumbing failures, often with a cap on the mold portion. In a federally declared disaster such as DR-4655, FEMA individual assistance may help with uninsured essential repairs, but it is not a substitute for insurance and it is not designed to fund full remediation. In every case, documentation and a written scope of work from your contractor make the process faster. We provide a written scope before starting any job.
How do I prepare before the next one?
Know whether you are in a floodplain; Three Forks, parts of Livingston, and riverside properties from Gallatin Gateway to Manhattan should assume yes. Keep a working sump pump with a battery backup and test it in February. Grade soil away from the foundation and keep snow from piling against it. Store basement belongings on shelves, not the floor. Install a vapor barrier and consider a dehumidifier in crawl spaces. And know who to call: a drying and remediation contractor on day one, not day ten.
If you have had water in your home from snowmelt, a river, a sump failure or a burst pipe, time matters. Request a free quote or call Call (727) 300-6656. We serve Bozeman, Livingston, Three Forks, Belgrade and the entire Gallatin Valley with same-day replies.