Bridge conditions in Humboldt County, California
399 inventoried bridges · 21 rated poor · 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
The federal inventory lists 399 bridges in Humboldt County: 169 rated good, 209 fair, and 21 poor.
- 21 of the 399 bridges in Humboldt County, California, are rated in poor condition (5.3%) in the 2025 National Bridge Inventory, as of .
- 169 bridges (42.4%) are rated good and 209 (52.4%) fair.
- The median Humboldt County bridge was built in 1965.
- The busiest poor-rated bridge is US Highway 101 NB over West End Rd Creek Ncrra (built 1929), carrying about 17,500 vehicles a day.
Good 42.4% · Fair 52.4% · Poor 5.3% of 399 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.
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| US Highway 101 NB over West End Rd Creek Ncrra | 1929 | 17,500 | Poor |
| U.S. Highway 101 over Dean Crk Rd & Dean Creek | 1967 | 5,000 | Poor |
| State Route 299 over Mad River | 1965 | 4,775 | Poor |
| Humboldt Hill Road over US Highway 101 | 1963 | 3,100 | Poor |
| State Park Road over South Fork Eel River | 1969 | 1,100 | Poor |
| Maple Creek Road over North Fork Mad River | 1928 | 624 | Poor |
| Hookton Road over Salmon Creek | 1922 | 486 | Poor |
| Bald Hills Road over Prairie Creek | 1957 | 479 | Poor |
| Mattole Rd over Mattole River | 1958 | 412 | Poor |
| Alderpoint Rd over South Dobbyn Creek | 1937 | 281 | Poor |
| Salmon Creek Road over Salmon Creek | 1959 | 226 | Poor |
| Holmes Flat Road over Larabee Low Level-eel Ri | 1960 | 100 | Poor |
| Zenia Bluff Rd over South Dobbyn Creek | 1949 | 85 | Poor |
| Lindley Road over Mattole River | 1925 | 50 | Poor |
| 33007: Butte Creek over Butte Creek | 1980 | 50 | Poor |
| No Data Entered over No Data Entered | 1980 | 50 | Poor |
| No Data Entered over No Data Entered | 1981 | 50 | Poor |
| Maple Creek Rd over Maple Creek | 1955 | 38 | Poor |
| Kneeland Rd over North Fork Yager Creek | 1964 | 10 | Poor |
| Albee Ck Camp over Albee Creek | 1986 | 10 | Poor |
| Grasshopper Lkt Rd over Squaw Creek | 1983 | 1 | Poor |
Busiest bridges in the county
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| U.S. Highway 101 over Orchard Ave | 1963 | 25,700 | Good |
| US Highway 101 SB over Palmer Blvd | 1958 | 22,000 | Fair |
| US Highway 101 NB over Palmer Blvd | 1958 | 22,000 | Fair |
| U.S. Highway 101 over US 101 On&off Ramp Ncrra | 1962 | 21,700 | Fair |
| U.S. Highway 101 over Salmon Creek | 1957 | 21,500 | Good |
| U.S. Highway 101 over Finch Creek Road | 1958 | 21,500 | Good |
| U.S. Highway 101 over Finch Creek Road | 1958 | 21,500 | Good |
| US Highway 101 over State Route 211 | 1957 | 20,400 | Fair |
| US Highway 101 SB over Mad River | 2011 | 18,500 | Good |
| US Highway 101 NB over Jacoby Creek | 1955 | 18,125 | Good |
Source: FHWA National Bridge Inventory, 2025. Counts cover inventoried highway bridges over 20 feet; ratings are reported by the state DOT.
All of California: California 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.