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Bridge conditions in Rock County, Minnesota

266 inventoried bridges · 5 rated poor · 2025 National Bridge Inventory

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

Rock County tracks close to typical: 5 of its 266 inventoried bridges (1.9%) are rated poor, against a national rate of about 7%.

5 of the 266 bridges in Rock County, Minnesota, are rated in poor condition (1.9%) in the 2025 National Bridge Inventory, as of August 20, 2026.
217 bridges (81.6%) are rated good and 44 (16.5%) fair.
The median Rock County bridge was built in 1997.
The busiest poor-rated bridge is Csah 6 over I 90 (built 1964), carrying about 1,006 vehicles a day.

Good 81.6% · Fair 16.5% · Poor 1.9% of 266 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
Csah 6 over I 90	1964	1,006	Poor
Csah 6 over Spring Brook	1957	920	Poor
Csah 3 over I 90	1965	910	Poor
Csah 8 over Mound Creek	1960	454	Poor
Csah 19 over Stream	1960	103	Poor

Busiest bridges in the county

Bridge	Built	Vehicles/day	Condition
I 90 over Spring Water Creek	1960	15,110	Fair
I 90 over Elk Creek	1964	11,392	Fair
I 90 over Beaver Creek	1960	11,300	Fair
I 90 over Beaver Creek	1971	11,300	Fair
I 90 over Stream	1964	9,344	Good
US 75 over I 90	1992	9,172	Fair
US 75 over Trib to Rock River	2014	7,872	Good
I 90 over BNSF RR	1960	7,555	Fair
I 90 over BNSF RR	1960	7,555	Fair
I 90 over Bnnr RR; Csah 4	1964	5,967	Fair

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

All of Minnesota: Minnesota 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.