Riverine Flood Risk in Montana
All Montana counties ranked by FEMA National Risk Index riverine flood score
Riverine Flood risk — rivers and streams overflowing their banks after heavy rain or snowmelt — is rated for 56 of 56 Montana counties in FEMA's National Risk Index. Yellowstone County carries the state's highest riverine flood score at 84.5, with $29M in expected annual riverine flood losses.
No Montana county reaches the High band for riverine flood, and expected annual losses from riverine flood total roughly $277M statewide. The full ranking below links to each county's complete 18-hazard risk profile.
County Rankings — Riverine Flood
| # | County | Riverine Flood Score | Rating | Ann. Freq. | Ann. Loss |
|---|---|---|---|---|---|
| 1 | Yellowstone County | Medium | 1.00 / yr | $29M | |
| 2 | Cascade County | Medium | 0.75 / yr | $25M | |
| 3 | Flathead County | Medium | 1.00 / yr | $24M | |
| 4 | Carbon County | Low | 0.64 / yr | $11M | |
| 5 | Missoula County | Low | 1.04 / yr | $19M | |
| 6 | Lincoln County | Low | 0.61 / yr | $7M | |
| 7 | Lewis and Clark County | Low | 1.07 / yr | $12M | |
| 8 | Gallatin County | Low | 0.43 / yr | $16M | |
| 9 | Sanders County | Low | 0.68 / yr | $6M | |
| 10 | Lake County | Low | 0.43 / yr | $7M | |
| 11 | Rosebud County | Low | 0.79 / yr | $4M | |
| 12 | Park County | Low | 0.25 / yr | $9M | |
| 13 | Big Horn County | Low | 0.68 / yr | $4M | |
| 14 | Ravalli County | Low | 0.79 / yr | $7M | |
| 15 | Chouteau County | Low | 0.29 / yr | $5M | |
| 16 | Blaine County | Low | 0.64 / yr | $4M | |
| 17 | Glacier County | Low | 0.29 / yr | $3M | |
| 18 | Hill County | Low | 0.21 / yr | $4M | |
| 19 | Phillips County | Low | 1.75 / yr | $3M | |
| 20 | Custer County | Low | 0.93 / yr | $4M | |
| 21 | Fergus County | Low | 0.50 / yr | $4M | |
| 22 | Beaverhead County | Low | 0.18 / yr | $3M | |
| 23 | Stillwater County | Low | 0.61 / yr | $6M | |
| 24 | Valley County | Very Low | 3.00 / yr | $4M | |
| 25 | Teton County | Very Low | 0.32 / yr | $4M | |
| 26 | Madison County | Very Low | 0.32 / yr | $4M | |
| 27 | Jefferson County | Very Low | 0.18 / yr | $4M | |
| 28 | Pondera County | Very Low | 0.29 / yr | $2M | |
| 29 | Dawson County | Very Low | 1.00 / yr | $3M | |
| 30 | Roosevelt County | Very Low | 1.39 / yr | $2M | |
| 31 | Richland County | Very Low | 1.11 / yr | $4M | |
| 32 | Silver Bow County | Very Low | 0.29 / yr | $3M | |
| 33 | Sweet Grass County | Very Low | 0.39 / yr | $3M | |
| 34 | Broadwater County | Very Low | 0.18 / yr | $2M | |
| 35 | Toole County | Very Low | 0.18 / yr | $2M | |
| 36 | Mineral County | Very Low | 0.18 / yr | $2M | |
| 37 | Powell County | Very Low | 0.29 / yr | $2M | |
| 38 | Musselshell County | Very Low | 0.89 / yr | $1M | |
| 39 | Sheridan County | Very Low | 0.50 / yr | $1M | |
| 40 | Judith Basin County | Very Low | 0.21 / yr | $2M | |
| 41 | Wheatland County | Very Low | 0.32 / yr | $1M | |
| 42 | Liberty County | Very Low | 0.07 / yr | $1M | |
| 43 | Granite County | Very Low | 0.29 / yr | $1M | |
| 44 | Deer Lodge County | Very Low | 0.25 / yr | $1M | |
| 45 | Meagher County | Very Low | 0.21 / yr | $1M | |
| 46 | Powder River County | Very Low | 0.89 / yr | $1M | |
| 47 | Prairie County | Very Low | 0.79 / yr | $626K | |
| 48 | McCone County | Very Low | 0.79 / yr | $870K | |
| 49 | Golden Valley County | Very Low | 0.46 / yr | $743K | |
| 50 | Fallon County | Very Low | 0.43 / yr | $1M | |
| 51 | Garfield County | Very Low | 1.07 / yr | $876K | |
| 52 | Carter County | Very Low | 0.39 / yr | $834K | |
| 53 | Wibaux County | Very Low | 0.61 / yr | $755K | |
| 54 | Daniels County | Very Low | 0.50 / yr | $670K | |
| 55 | Treasure County | Very Low | 0.39 / yr | $598K | |
| 56 | Petroleum County | Very Low | 0.82 / yr | $398K |
56 Montana counties with measurable riverine flood risk. See the national riverine flood ranking or all Montana counties by overall risk.
Frequently Asked Questions
Which Montana county has the highest riverine flood risk?
Yellowstone County has the highest FEMA riverine flood risk score in Montana at 84.5 (Medium), with $29M in expected annual losses and about 1.00 events per year.
How many Montana counties face significant riverine flood risk?
56 Montana counties record measurable riverine flood risk in FEMA's National Risk Index; 0 of them are rated High or Very High.