County Highway #23 over Oak Ck
Mellette County, South Dakota · rated Fair in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- County Highway #23 over Oak Ck in Mellette County, South Dakota, 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 1957, making it 68 years old at the 2025 inventory.
- It carries about 63 vehicles a day (traffic count year 2022).
- Its listed owner is the county highway agency.
- It is one of 17 of the 28 inventoried bridges in Mellette County rated fair (60.7%); 2 (7.1%) 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.
View this bridge on a map → (43.43663, -100.29384)
Component ratings
| Component | Rating (2025) | FHWA scale meaning |
|---|---|---|
| Deck | 6 | Satisfactory condition |
| Superstructure | 6 | Satisfactory condition |
| Substructure | 6 | Satisfactory condition |
Bridge details
| Structure | Continuous concrete slab |
| Length | about 128 ft |
| Location | 3S Mosher |
| NBI structure number | 000000048480298 |
| Condition class | Fair |
Source: FHWA National Bridge Inventory, 2025 data as reported by the South Dakota department of transportation.
Busiest bridges in Mellette County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| Irr Ar US083 over Horse Head Ck | 1966 | 1,525 | Fair |
| Irr Ar US083 over Ck | 1965 | 1,525 | Good |
| US083 over Little White Rv | 2022 | 1,188 | Good |
| US083 over White Rv | 2021 | 1,188 | Good |
| SD044 over Little White Rv | 1973 | 739 | Fair |
| Irr Ar SD044 over Corn Ck | 1980 | 420 | Good |
All bridges nearby: Mellette County, SD bridge conditions · every bridge in Mellette County · South Dakota bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.