Idaho Statewide Rule

Idaho Floodplain Management Framework Authorizes Local Rules

Heavy RestrictionsApplies statewide across Idaho (2026)

Key Facts

Statute: Idaho Code 46-1020
Coordinator: Idaho Water Resources
Federal floor: 44 CFR 60.3
Elevation standard: Base flood elevation
NFIP participation: Most ID cities

Last verified: August 21, 2026Source: Idaho Legislature

Summary

Idaho Code 46-1020 through 46-1024 establishes the statewide framework directing local governments to adopt floodplain management ordinances meeting NFIP minimum standards. The Idaho Department of Water Resources coordinates compliance, and local rules must satisfy federal flood insurance program requirements.

Subject to the availability of adequate mapping and data to properly identify the floodplains, if any, within its jurisdiction, each local government is encouraged to adopt a floodplain map and floodplain management ordinance which identifies these floodplains and which requires, at a minimum, that any development in a floodplain must be constructed at a flood protection elevation and/or have adequate floodproofing. The local government may regulate all mapped and unmapped floodplains within its jurisdiction. Nothing in this act shall prohibit a local government from adopting more restrictive standards than those contained in this chapter.

Source: Idaho LegislatureView official code

Full Breakdown

Idaho Code 46-1020 declares state policy that local units of government have primary responsibility for floodplain land-use regulation. Sections 46-1020 through 46-1024 authorize cities and counties to adopt floodplain management ordinances that identify special flood hazard areas and impose minimum development standards. Communities participating in the National Flood Insurance Program (NFIP) must adopt and enforce ordinances requiring elevation or floodproofing of new structures, anchoring, and subdivision review consistent with 44 CFR 60.3. The Idaho Department of Water Resources serves as the State NFIP Coordinator, providing technical assistance and reviewing local ordinances. While day-to-day administration is local, federal NFIP minimums effectively bind every participating Idaho community.

Violations & Penalties

Building in a special flood hazard area without proper elevation or local permit can void NFIP flood insurance, trigger fines under local ordinance, and require structure removal or retrofit.

Frequently Asked Questions

Does Idaho have a state floodplain ordinance?

No single statewide ordinance. Idaho Code 46-1020 directs cities and counties to adopt local floodplain ordinances meeting NFIP minimums. The Idaho Department of Water Resources reviews and supports compliance.

Do I need a permit to build in a flood zone?

Yes. Almost every Idaho community participating in NFIP requires a floodplain development permit before any construction, fill, or grading inside a mapped Special Flood Hazard Area, regardless of structure type.

What if my city is not in NFIP?

Federally backed mortgages cannot be used in mapped flood zones, and federal disaster assistance is limited. Idaho strongly encourages all flood-prone communities to enroll under the framework in Idaho Code 46-1020.

Sources

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