Idaho Floodplain Management Framework Authorizes Local Rules

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.

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.