US 89 over Mill Coulee Canal
FairPosted for loadCascade County, Montana · 5M N Fort Shaw · Structure no. P00003014+05331
- Built
- 1940
- 85 years old
- Condition
- Fair
- inspected October 2024
- Type
- Stringer/Multi-beam or Girder
- Wood or Timber
- Length
- 25 ft
- 1 main span
- Daily traffic
- 1,757
- 2023 count
- Owner
- State
- State Highway Agency
About this bridge
US 89 over Mill Coulee Canal is a wood or timber stringer/multi-beam or girder carrying US 89 over Mill Coulee Canal in Cascade County, Montana. It was built in 1940, so it is 85 years old, older than the Montana average of 47 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. Its operating status is: posted for load restriction.
It carries about 1,757 vehicles a day, roughly 3% of them trucks, projected to reach 1,845 by 2043. The structure is 25 ft (7.6 m) long and 31 ft wide. If it were closed, the detour would be 18 mi (29 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 | 5 Fair | All primary structural elements are sound but may have minor section loss, cracking, spalling or scour. |
| 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 US 89 over Mill Coulee Canal built?
It was built in 1940, making it 85 years old in 2025.
What condition is US 89 over Mill Coulee Canal 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 October 2024.
How much traffic does US 89 over Mill Coulee Canal carry?
About 1,757 vehicles per day (2023 count), of which roughly 3% are trucks.
How long is US 89 over Mill Coulee Canal?
The structure is 25 ft (7.6 m) long with a longest span of 25 ft (7.6 m) and a deck 31 ft wide.
Who owns US 89 over Mill Coulee Canal?
It is owned by the State Highway Agency.