Structure 3C0071 · Modoc County, CA
Carries IRR Co RD 87 over Mamath Slough, 0.5 Mi NE CR 91.
Set by its lowest-rated component: Deck and Superstructure and Substructure at 7 of 9.
How ratings work23 ft end to end. Lengths are drawn to scale; at this length a semi-truck would be a speck. Each part is colored by its latest inspection rating. The inventory records lengths but not heights or the layout of the shorter spans, so those are drawn as typical for a slab bridge.
| State | California |
| County | Modoc |
| Location | 0.5 Mi NE CR 91 |
| Carries | IRR Co RD 87 |
| Crosses | Mamath Slough |
| Coordinates | 41.21318, -121.13624 |
| Material | Concrete |
| Design | Slab |
| Total Length | 23.0 ft (7 m) |
| Max Span | 20.0 ft (6.1 m) |
| Deck Width | 28.9 ft (8.8 m) |
| Deck Area | 61.6 sq m |
| Main Spans | 1 |
| Year Built | 1955 |
| Avg Daily Traffic | 255 (2006) |
| Truck Traffic | 10% |
| Lanes On Bridge | 2 |
| Last Inspection | April 2023 |
| Inspection Frequency | Every 48 months |
| Owner | County Highway Agency |
| Historical Significance | Bridge is not eligible for the National Register |
| Scour Critical | 8 — Stable, low risk |
| Structure Number | 03C0071 |
Inspectors rate each major part of a bridge (the deck you drive on, the superstructure of beams that holds it up, and the substructure of piers and abutments beneath) on a 0–9 scale. A bridge's overall condition is its lowest of those ratings, so one deteriorated component makes the whole bridge "poor."
A poor rating is not a closure. It means the bridge is flagged for priority repair or replacement; bridges judged unsafe are closed or posted with weight limits. The waterway (channel) rating is reported, but it does not count toward the overall classification.