SD1804 over Blue Blanket Ck

Walworth County, South Dakota · rated Fair in the 2025 National Bridge Inventory

United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled August 20, 2026

• SD1804 over Blue Blanket Ck in Walworth County, South Dakota, is rated in fair condition in the 2025 National Bridge Inventory (as of August 20, 2026).
• Its lowest-rated component is the substructure, rated 5 (fair condition) on the 0-9 scale.
• It was built in 1961, making it 64 years old at the 2025 inventory.
• It carries about 272 vehicles a day (traffic count year 2024).
• Its listed owner is the state highway agency.
• It is one of 21 of the 33 inventoried bridges in Walworth County rated fair (63.6%); 1 (3.0%) are rated poor.
• Its traffic status in the 2025 inventory is open, no restriction (NBI item 41).
• Its class is unchanged from 2024 (fair), but component ratings moved: substructure 6 to 5.
• Its most recent inspection on record is dated December 2024, on a 24-month routine inspection cycle.
• A fair rating means the lowest-rated major component scores 5 or 6 on FHWA's 0-9 scale: some deterioration or minor section loss, but the structure is sound. It is the middle class, not a warning.

View this bridge on a map → (45.50957, -100.32199)

Component ratings

Bridge details

Source: FHWA National Bridge Inventory, 2025 data as reported by the South Dakota department of transportation.

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Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.