Bridge conditions in Lyon County, Iowa
273 inventoried bridges · 70 rated poor · 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
Of the 273 Lyon County bridges in the federal inventory, 70 carry a poor rating. That 25.6% share is roughly 4x the national average.
- 70 of the 273 bridges in Lyon County, Iowa, are rated in poor condition (25.6%) in the 2025 National Bridge Inventory, as of .
- 104 bridges (38.1%) are rated good and 99 (36.3%) fair.
- The median Lyon County bridge was built in 1978.
- The busiest poor-rated bridge is A26 (180TH St) over Big Sioux River (built 1977), carrying about 1,017 vehicles a day.
Good 38.1% · Fair 36.3% · Poor 25.6% of 273 bridges
Bridges rated poor
Every bridge in the county with a poor rating, busiest first. Poor means a major component is rated 4 or lower on FHWA's 0-9 scale; it is a repair flag, not a closure notice.
Busiest bridges in the county
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| Ia 9 over Stream | 1980 | 4,840 | Good |
| Ia 9 over Stream | 1940 | 4,520 | Fair |
| Ia 9 over Bloodrun Creek | 1977 | 4,520 | Fair |
| US 75 & Ia 9 over Moon Creek | 1972 | 4,400 | Fair |
| Ia 9 over Rock River | 1974 | 3,920 | Fair |
| Ia 9 over Mud Creek | 1975 | 3,270 | Fair |
| Ia 9 over Stream | 1982 | 3,180 | Fair |
| Ia 9 over over BNSF RR | 1982 | 3,180 | Fair |
| Ia 9 over Moon Creek | 1974 | 3,180 | Fair |
| US 75 over Rock River | 1975 | 2,620 | Fair |
Source: FHWA National Bridge Inventory, 2025. Counts cover inventoried highway bridges over 20 feet; ratings are reported by the state DOT.
Every bridge in Lyon County → - all 273, busiest first, each with its own condition record.
All of Iowa: Iowa bridge conditions by county · every download on the data page.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.