Riverine Flood Risk in Idaho
All Idaho 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 44 of 44 Idaho counties in FEMA's National Risk Index. Ada County carries the state's highest riverine flood score at 89.8, with $63M in expected annual riverine flood losses.
No Idaho county reaches the High band for riverine flood, and expected annual losses from riverine flood total roughly $383M 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 | Ada County | Medium | 0.79 / yr | $63M | |
| 2 | Bonner County | Medium | 0.61 / yr | $28M | |
| 3 | Kootenai County | Medium | 1.21 / yr | $32M | |
| 4 | Canyon County | Medium | 0.39 / yr | $24M | |
| 5 | Bonneville County | Medium | 0.61 / yr | $24M | |
| 6 | Shoshone County | Medium | 0.93 / yr | $15M | |
| 7 | Idaho County | Low | 0.57 / yr | $12M | |
| 8 | Blaine County | Low | 1.04 / yr | $15M | |
| 9 | Lemhi County | Low | 0.64 / yr | $8M | |
| 10 | Bingham County | Low | 0.50 / yr | $9M | |
| 11 | Owyhee County | Low | 0.89 / yr | $5M | |
| 12 | Madison County | Low | 0.64 / yr | $9M | |
| 13 | Nez Perce County | Low | 0.54 / yr | $12M | |
| 14 | Custer County | Low | 0.57 / yr | $5M | |
| 15 | Valley County | Low | 0.43 / yr | $8M | |
| 16 | Clearwater County | Low | 0.29 / yr | $5M | |
| 17 | Cassia County | Low | 0.75 / yr | $8M | |
| 18 | Bannock County | Low | 1.86 / yr | $8M | |
| 19 | Twin Falls County | Low | 0.32 / yr | $8M | |
| 20 | Latah County | Low | 1.07 / yr | $8M | |
| 21 | Benewah County | Low | 0.86 / yr | $5M | |
| 22 | Boundary County | Low | 0.50 / yr | $5M | |
| 23 | Boise County | Low | 0.82 / yr | $6M | |
| 24 | Fremont County | Low | 0.50 / yr | $7M | |
| 25 | Washington County | Low | 0.61 / yr | $3M | |
| 26 | Jefferson County | Low | 0.39 / yr | $6M | |
| 27 | Adams County | Low | 0.29 / yr | $3M | |
| 28 | Gem County | Low | 0.36 / yr | $4M | |
| 29 | Payette County | Very Low | 0.25 / yr | $5M | |
| 30 | Minidoka County | Very Low | 0.18 / yr | $4M | |
| 31 | Jerome County | Very Low | 0.14 / yr | $3M | |
| 32 | Elmore County | Very Low | 0.71 / yr | $5M | |
| 33 | Teton County | Very Low | 0.18 / yr | $4M | |
| 34 | Gooding County | Very Low | 0.18 / yr | $3M | |
| 35 | Franklin County | Very Low | 0.25 / yr | $3M | |
| 36 | Lincoln County | Very Low | 0.14 / yr | $2M | |
| 37 | Lewis County | Very Low | 0.14 / yr | $1M | |
| 38 | Caribou County | Very Low | 0.36 / yr | $2M | |
| 39 | Butte County | Very Low | 0.39 / yr | $1M | |
| 40 | Power County | Very Low | 0.82 / yr | $1M | |
| 41 | Bear Lake County | Very Low | 0.32 / yr | $1M | |
| 42 | Oneida County | Very Low | 0.61 / yr | $940K | |
| 43 | Camas County | Very Low | 0.18 / yr | $516K | |
| 44 | Clark County | Very Low | 0.29 / yr | $506K |
44 Idaho counties with measurable riverine flood risk. See the national riverine flood ranking or all Idaho counties by overall risk.
Frequently Asked Questions
Which Idaho county has the highest riverine flood risk?
Ada County has the highest FEMA riverine flood risk score in Idaho at 89.8 (Medium), with $63M in expected annual losses and about 0.79 events per year.
How many Idaho counties face significant riverine flood risk?
44 Idaho counties record measurable riverine flood risk in FEMA's National Risk Index; 0 of them are rated High or Very High.