Home › Idaho › Valley County › Dam Road over Cascade Dam Spillway

Dam Road over Cascade Dam Spillway

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

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

Dam Road over Cascade Dam Spillway in Valley County, Idaho, is rated in fair condition in the 2025 National Bridge Inventory (as of August 20, 2026).
Its lowest-rated component is the deck, rated 6 (satisfactory condition) on the 0-9 scale.
It was built in 1947, making it 78 years old at the 2025 inventory.
It carries about 100 vehicles a day (traffic count year 2020).
It is one of 71 of the 153 inventoried bridges in Valley County rated fair (46.4%); 10 (6.5%) 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	Steel stringer or multi-beam girder
Length	about 47 ft
Location	Cascade Dam
NBI structure number	15CAS001
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 N. Fk. Payette River	2013	7,800	Fair
SH 55 over N.fk.payette R;lardo	2014	7,400	Fair
SH 55 over Lake Fork Creek	1985	6,500	Fair
SH 55 over Boulder Creek	1999	6,000	Fair
SH 55 over Lake Fork Creek Canal	1998	6,000	Fair
SH 55 over N. Fk. Payette River	2015	5,700	Good