Bridge conditions in Dewey County, South Dakota

27 inventoried bridges · 4 rated poor · 2025 National Bridge Inventory

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

Dewey County has 4 bridges rated poor out of 27 inventoried, a 14.8% share that puts it well above the national rate of about 7%.

4 of the 27 bridges in Dewey County, South Dakota, are rated in poor condition (14.8%) in the 2025 National Bridge Inventory, as of August 20, 2026.
15 bridges (55.6%) are rated good and 8 (29.6%) fair.
The median Dewey County bridge was built in 1988.
The busiest poor-rated bridge is Irr Bia Rte 2 over Red Water Creek (built 1961), carrying about 180 vehicles a day.

Good 55.6% · Fair 29.6% · Poor 14.8% of 27 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
Irr Bia Rte 2 over Red Water Creek	1961	180	Poor
Irr Bia Rte 7 over Virgin Creek	1961	105	Poor
Fas 6247 over Bear Creek	1960	103	Poor
Irr Bia Rte 7 over No Mouth Creek	1960	70	Poor

Busiest bridges in the county

Bridge	Built	Vehicles/day	Condition
Irr US212 over Little Bear Ck	2023	1,291	Good
Irr SD020 over Ck	1997	890	Good
Irr SD020 over Ck	1997	890	Good
Irr SD063 over Moreau Rv	1971	717	Fair
Irr US212 over Virgin Ck	1990	601	Good
Irr US212 over Virgin Ck	1988	601	Good
Irr SD020 over Little Moreau Rv	1993	598	Good
Irr Bia Rte 3 over Veo Creek	2016	550	Good
Irr County Road over Creek	2020	451	Good
Irr Bia Rte 3 over Moreau River	1987	305	Good

Source: FHWA National Bridge Inventory, 2025. Counts cover inventoried highway bridges over 20 feet; ratings are reported by the state DOT.

All of South Dakota: South Dakota 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.