Watmaugh Road over Nathanson Creek
FairSonoma County, California · 0.5 MI E SR 12 · Structure no. 20C0255
- Built
- 1920
- 105 years old, rebuilt 1970
- Condition
- Fair
- inspected April 2024
- Type
- Tee Beam
- Concrete
- Length
- 34 ft
- 1 main span
- Daily traffic
- 1,000
- 2015 count
- Owner
- County
- County Highway Agency
About this bridge
Watmaugh Road over Nathanson Creek is a concrete tee beam carrying Watmaugh Road over Nathanson Creek in Sonoma County, California. It was built in 1920 and reconstructed in 1970, so it is 105 years old, older than the California average of 54.8 years.
The most recent inspection reported to the Federal Highway Administration rates it in fair condition with a lowest component rating of 5 out of 9. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.
It carries about 1,000 vehicles a day, roughly 1% of them trucks, projected to reach 3,061 by 2046. The structure is 34 ft (10.4 m) long and 33 ft wide. If it were closed, the detour would be 3.1 mi (5 km).
Location
Open in Google MapsCondition and inspection
The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.
| Component | Rating | Meaning |
|---|---|---|
| Deck | 7 Good | Some minor problems. |
| Superstructure | 7 Good | Some minor problems. |
| Substructure | 5 Fair | All primary structural elements are sound but may have minor section loss, cracking, spalling or scour. |
| Channel and channel protection | 6 Satisfactory | Structural elements show some minor deterioration. |
Structure
Traffic and service
Ownership and planned work
Frequently asked questions
When was Watmaugh Road over Nathanson Creek built?
It was built in 1920, making it 105 years old in 2025. It was reconstructed in 1970.
What condition is Watmaugh Road over Nathanson Creek in?
The National Bridge Inventory rates it in fair condition. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound. The last reported inspection was in April 2024.
How much traffic does Watmaugh Road over Nathanson Creek carry?
About 1,000 vehicles per day (2015 count), of which roughly 1% are trucks.
How long is Watmaugh Road over Nathanson Creek?
The structure is 34 ft (10.4 m) long with a longest span of 33 ft (10.1 m) and a deck 33 ft wide.
Who owns Watmaugh Road over Nathanson Creek?
It is owned by the County Highway Agency.