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SH 21 over Clear Creek;at Lowman

Boise County, Idaho · rated Fair in the 2025 National Bridge Inventory

United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled August 20, 2026

SH 21 over Clear Creek;at Lowman in Boise County, Idaho, is rated in fair condition in the 2025 National Bridge Inventory (as of August 20, 2026).
Its lowest-rated component is the substructure, rated 5 (fair condition) on the 0-9 scale.
It was built in 1939, making it 86 years old at the 2025 inventory.
It carries about 1,200 vehicles a day (traffic count year 2023).
Its listed owner is the state highway agency.
It is one of 39 of the 89 inventoried bridges in Boise County rated fair (43.8%); 5 (5.6%) are rated poor.
A fair rating means the lowest-rated major component scores 5 or 6 on FHWA's 0-9 scale: some deterioration or minor section loss, but the structure is sound. It is the middle class, not a warning.

Component ratings


Structure	Continuous steel stringer or multi-beam girder
Length	about 149 ft
Location	at Lowman
NBI structure number	000000000012890
Condition class	Fair

Source: FHWA National Bridge Inventory, 2025 data as reported by the Idaho department of transportation.

Bridge	Built	Vehicles/day	Condition
SH 55 over McLEOD WAY	2024	10,500	Good
SH 55 over Payette River	2021	8,800	Good
SH 55 over Power Canal	1994	8,800	Good
SH 55 over Uprr;horseshoe Bend Op	1971	7,800	Fair
SH 55 over Payette River	1971	7,800	Fair
SH 55 over S.fk.payette River	1955	7,300	Fair