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.

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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.

Known adaptation measures i
Properties protected by adaptation i

Top adaptation measures in Idaho:

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
% chance
of flooding
in a given year
% chance
of flooding
over 30 years
100 year
500 year

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.

Select a projected flood risk:

More likely to occurArrow right
Arrow leftMore properties impacted

Approx. properties have a 0.2% chance of some amount of water reaching their building in 2022.


Depth of flooding (feet)

Approx. properties have a 0.2% chance of some amount of water reaching their building in 2022.


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
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    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
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    Restoring or constructing new marsh or wetlands provides areas for water to be stored, therefore reducing flooding.

  • Rain Gardens and Bioswales
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    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
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    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
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    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

Source: NASA Earth Exchange Global Daily Downscaled Projections (NEX-GDDP).

Rise in inches, compared to 1980-2010 average. i

+5 in.

Place with highest sea level rise (inches)

14.4Grand Isle, LA
10.3Galveston Pier 21, TX
9.4Ocean City Inlet, MD
9.1New Canal Station, LA
8.7Lewisetta, VA
Source: Kopp et al, 2017. Evolving Understanding of Antarctic Ice‐Sheet Physics and Ambiguity in Probabilistic Sea‐Level Projections.

Temperatures in degrees Fahrenheit. Increase in comparison to the 1980-2010 average. i

Source: NOAA National Data Buoy Center and Schmidt et al, 2014., Configuration and assessment of the GISS ModelE2 contributions to the CMIP5 archive.

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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