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Bridge conditions in Ziebach County, South Dakota

30 inventoried bridges · 3 rated poor · 2025 National Bridge Inventory

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

Of the 30 Ziebach County bridges in the federal inventory, 3 carry a poor rating. That 10.0% share is roughly 1x the national average.

3 of the 30 bridges in Ziebach County, South Dakota, are rated in poor condition (10.0%) in the 2025 National Bridge Inventory, as of August 20, 2026.
7 bridges (23.3%) are rated good and 20 (66.7%) fair.
The median Ziebach County bridge was built in 1969.
The busiest poor-rated bridge is Irr SD063 over Dupree Ck (built 1961), carrying about 590 vehicles a day.

Good 23.3% · Fair 66.7% · Poor 10.0% of 30 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 SD063 over Dupree Ck	1961	590	Poor
Four Corners Road over Ck	1930	16	Poor
Irr County Road over Bear Ck	1935	10	Poor

Busiest bridges in the county

Bridge	Built	Vehicles/day	Condition
Irr US212 over Ck	1954	1,291	Fair
Irr US212 over Bear Ck	1954	1,130	Fair
Irr US212 over Bear Ck	1955	1,083	Fair
Irr Bia Rte 6 over Ash Creek	1968	814	Good
Irr SD063 over Rudy Ck Tributary	1994	590	Fair
Irr SD063 over Rudey Ck	1993	590	Fair
Irr SD063 over Dupree Ck	1961	590	Poor
Irr SD065 over Ck	1995	580	Fair
Irr SD065 over Bear Ck	1984	580	Good
Irr SD065 over Moreau Rv	1972	580	Fair

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.