Summary
Flood risk overview for Idaho
There are 160,375 properties in Idaho that have greater than a 26% chance of being severely affected by flooding over a the next 30 years. This represents 16% of all properties in the state.
In addition to damage on properties, flooding can also cut off access to utilities, emergency services, transportation, and may impact the overall economic well-being of an area.
Explore the maps below to learn more about the homes, roads, businesses, and services at risk in Idaho.
Current Protections
There are solutions to protect Idaho.
Communities that adapt to higher risks can limit damage and lower flood insurance costs. Idaho is already investing in flood risk reduction projects, but more may be needed. Learn more about solutions.
Where to Start
Lowering flood risk starts with higher standards
Some places plan to a higher standard (a "500 year" standard) that lowers the number of properties at severe risk. Protecting homes to this level would reduce the risk to the 160,375 severely affected properties by 77%.
Flood Event |
% chanceof floodingin a given year |
% chanceof floodingover 30 years | |||
|---|---|---|---|---|---|
100 year | 1% | 26% | |||
500 year | .02% | 6% |
Flood Risk Explorer
Flood risks vary by depth and likelihood.
Deeper floods from major events, like hurricanes, are less likely to occur, but cause greater damage than more shallow flood events, like heavy rains.
Approx. properties have a 0.2% chance of some amount of water reaching their building in 2021.
Depth of flooding (feet)
Note: 19,289 properties in this area are protected by adaptation. While the above projections take into account this protection, risks may substantially increase in the event of adaptation failure.
Community Solutions
Solutions can protect Idaho.
Individuals, mayors, governors, and Congress can work together to build protections before flooding, build back stronger after flooding, and create plans that future-proof communities. Learn more about solutions.
Green infrastructure is a cost-effective and sustainable flood management approach that gathers and removes water at its source.
- Open Spaces
By providing space for managed flooding, communities can reduce the flood risks for homes and businesses. These spaces can include cemeteries, golf courses, and parks.
- Marshes and Wetlands
Restoring or constructing new marsh or wetlands provides areas for water to be stored, therefore reducing flooding.
- Rain Gardens and Bioswales
Rain gardens reduce flash flooding by collecting rainwater and allowing time for the water to be absorbed or carried away. Bioswales are larger but functionally similar, and usually a part of a larger stormwater drainage system.
- Beach Dunes and Renourishment
Beaches and dunes work as natural walls to reduce the impact of storm surges. Adding sand to make beaches bigger helps limit coastal erosion and protect communities from flooding.
- Natural Barriers
Restoring and building up natural infrastructure such as barrier islands, oyster and coral reefs, mangroves, seagrass, and salt marshes is a cost-effective and eco-friendly way to reduce flood risks.
Environmental Changes
Flood risks are increasing because of the environment.
A changing environment means higher seas, new weather patterns, and stronger storms. As the atmosphere warms, there is more evaporation and more water available when it rains.
A warmer atmosphere also means warmer oceans, which can intensify flooding from hurricanes and offshore storms. Sea level rise also increases coastal flood risks, as higher seas mean there's more water available when high tides and coastal storms cause flooding.
Learn more about the environmental factors increasing flood risk.
Select year of projection
Change in extreme rain events compared to 1980-2010 average. i
National Flood Risks
Flooding is a national issue.
Across the United States, more than 16.1 million properties are already at substantial risk of flooding this year, and approximately 154.5K of those properties are in Idaho.
Total properties with substantial risk i
How flood risk will change in 30 years
Because of changes in the environment, more than 17.8 million properties will have substantial risk in 30 years. Idaho will see a 7.6% increase in the number of properties with substantial risk in the next 30 years.
30-year change in number of properties at substantial risk i
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