Bonneville County, Idaho Natural Disaster Risk
FEMA National Risk Index assessment · ID
MediumComposite Risk Score
National percentile: 82th
Bonneville County faces medium composite natural disaster risk (NRI Risk Index score 82.4, 82th national percentile), driven primarily by avalanche and earthquake exposure. Expected annual loss across all 18 hazard types is $65M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
Overall natural disaster risk in Bonneville County is medium, with a National Risk Index score of 82.4 out of 100 — placing it in the 82nd national percentile and near the national midpoint for natural-disaster risk. The score blends Expected Annual Loss, Social Vulnerability, and Community Resilience across all 18 FEMA hazard types.
Risk here concentrates in avalanche (fast-moving snow and debris sliding down steep mountain slopes) at High risk — $4M in expected annual loss and about 0.27 events per year; earthquake (ground shaking from sudden movement along geologic faults) at Medium risk — $16M in expected annual loss and about 0.03 events per year; and landslide (downhill movement of rock, soil, and debris on unstable slopes) at Medium risk — $142K in expected annual loss and about 1.53 events per year. Across all hazards, FEMA estimates $65M in expected annual loss for a population of 124K.
Beyond physical exposure, Bonneville County has a very low social vulnerability rating (how susceptible the population is to harm) and a very high community resilience rating (its capacity to prepare for and recover from disasters). A less vulnerable population paired with strong resilience helps the community absorb and recover from events.
History supports the rating: Bonneville County has received 7 federal disaster declarations since 1964, including 2 for biological events and 2 for flood events. The most recent was Covid-19 Pandemic (biological), declared in April 2020.
Among 44 Idaho counties, Bonneville County ranks #2 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Avalanche | High | 0.27 / yr | $4M |
| Earthquake | Medium | 0.03 / yr | $16M |
| Landslide | Medium | 1.53 / yr | $142K |
| Cold Wave | High | 1.43 / yr | $12M |
| Wildfire | Medium | 0.01 / yr | $2M |
| Lightning | High | 35.96 / yr | $2M |
| Hail | Medium | 0.43 / yr | $2M |
| Heat Wave | Medium | 0.65 / yr | $2M |
| Riverine Flood | Medium | 0.61 / yr | $24M |
| Volcanic Activity | Very Low | 0.00 / yr | $163 |
| Winter Weather | Medium | 24.32 / yr | $150K |
| Strong Wind | Low | 0.76 / yr | $612K |
| Ice Storm | Very Low | 0.01 / yr | $35K |
| Drought | Very Low | 62.94 / yr | $5K |
| Tornado | Very Low | 0.18 / yr | $217K |
| Coastal Flood | Very Low | 0.00 / yr | $0 |
| Hurricane | Very Low | 0.00 / yr | $0 |
| Tsunami | Very Low | 0.00 / yr | $0 |
Disaster History
Bonneville County has received 7 federal disaster declarations since 1964, most recently Covid-19 Pandemic in April 2020. Most frequent causes: Biological (2), Flood (2), Fire (1).
| Declared | Type | Disaster |
|---|---|---|
| April 2020 | Biological | Covid-19 Pandemic |
| March 2020 | Biological | Covid-19 |
| August 2016 | Fire | Henrys Creek Fire |
| September 2005 | Hurricane | Hurricane Katrina |
| June 1997 | Severe Storm | Severe Storms, Snowmelt, Land/Mud Slides, Flooding |
| June 1976 | Flood | Dam Collapse, Flooding |
| December 1964 | Flood | Heavy Rains & Flooding |
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for Bonneville County?
Bonneville County has a composite FEMA National Risk Index score of 82.4 out of 100, placing it in the Medium category and the 82th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Bonneville County?
The three highest-rated hazards are Avalanche (High, $4M EAL), Earthquake (Medium, $16M EAL), Landslide (Medium, $142K EAL). These account for most of the county's expected annual losses.
How does Bonneville County compare to other Idaho counties?
Bonneville County ranks #2 of 44 Idaho counties for overall natural disaster risk, with a medium rating.
How many federally declared disasters has Bonneville County had?
FEMA records 7 federal disaster declarations for Bonneville County since 1964, most often 2 for biological events and 2 for flood events. The most recent was Covid-19 Pandemic, declared in April 2020.
What does Expected Annual Loss (EAL) mean?
EAL is FEMA's estimate of average annual dollar losses from natural hazards, calculated from historical event data and exposure models. Bonneville County's $65M EAL is a statistical average, not a guarantee for any specific year or address.