Irr C106 over Ninemile Slough
Harney County, Oregon · rated Good in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- Irr C106 over Ninemile Slough in Harney County, Oregon, is rated in good condition in the 2025 National Bridge Inventory (as of ).
- Its lowest-rated component is the deck, rated 8 (very good condition) on the 0-9 scale.
- It was built in 2006, making it 19 years old at the 2025 inventory.
- It carries about 179 vehicles a day (traffic count year 2020).
- Its listed owner is the county highway agency.
- It is one of 65 of the 128 inventoried bridges in Harney County rated good (50.8%); 2 (1.6%) are rated poor.
- Its traffic status in the 2025 inventory is open, no restriction (NBI item 41).
- Its condition class and component ratings are unchanged from the 2024 inventory.
- Its most recent inspection on record is dated September 2024, on a 24-month routine inspection cycle.
- A good rating means every major component - deck, superstructure, substructure, or culvert - is rated 7 or higher on FHWA's 0-9 scale: no more than minor problems.
View this bridge on a map → (43.54871, -118.82216)
Component ratings
| Component | Rating (2024) | Rating (2025) | FHWA scale meaning |
|---|---|---|---|
| Deck | 8 | 8 | Very good condition |
| Superstructure | 8 | 8 | Very good condition |
| Substructure | 8 | 8 | Very good condition |
Bridge details
| Structure | Prestressed concrete slab |
| Length | about 36 ft |
| Location | 046 US Hwy 20 |
| NBI structure number | 20455 C10600461 |
| Condition class | Good |
| Traffic status (item 41) | Open, no restriction |
| Last inspection (item 90) | September 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 Oregon department of transportation.
Busiest bridges in Harney County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| US 20 (hwy 007) over Silvies River | 1999 | 2,834 | Good |
| US 20 (hwy 007) over Willow Creek | 1993 | 2,792 | Fair |
| US 20 (hwy 007) over Poison Creek(susans Br) | 1966 | 2,332 | Good |
| US 20 (hwy 007) over Foley Slough | 1999 | 2,332 | Good |
| US 20 (hwy 007) over Silver Creek | 1956 | 2,325 | Fair |
| US 20 (hwy 007) over Miller Creek | 2004 | 2,325 | Good |
All bridges nearby: Harney County, OR bridge conditions · every bridge in Harney County · Oregon bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.