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
- Dam Road over Cascade Dam Spillway in Valley County, Idaho, is rated in fair condition in the 2025 National Bridge Inventory (as of ).
- 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.
- Its traffic status in the 2025 inventory is posted for load (NBI item 41).
- Its condition class and component ratings are unchanged from the 2024 inventory.
- Its most recent inspection on record is dated July 2024, on a 24-month routine inspection cycle.
- 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.
View this bridge on a map → (44.52463, -116.04958)
Component ratings
| Component | Rating (2024) | Rating (2025) | FHWA scale meaning |
|---|---|---|---|
| Deck | 6 | 6 | Satisfactory condition |
| Superstructure | 7 | 7 | Good condition |
| Substructure | 7 | 7 | Good condition |
Bridge details
| Structure | Steel stringer or multi-beam girder |
| Length | about 47 ft |
| Location | Cascade Dam |
| NBI structure number | 15CAS001 |
| Condition class | Fair |
| Traffic status (item 41) | Posted for load |
| Last inspection (item 90) | July 2024 |
| Inspection interval (item 91) | 24 months |
| Scour (item 113) | 8: foundations stable, scour above the top of the footing |
Source: FHWA National Bridge Inventory, 2025 data as reported by the Idaho department of transportation.
Busiest bridges in Valley County
| 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 |
All bridges nearby: Valley County, ID bridge conditions · every bridge in Valley County · Idaho bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.