Scour Critical Bridges in Idaho
215 bridges in Idaho at risk from water erosion around foundations.
Scour Critical Bridges
Scour is the erosion of soil and rock around a bridge's foundation caused by moving water. When foundations are exposed or undermined, a bridge can collapse even if its deck and superstructure are in good condition. Scour is the leading cause of bridge failures in the US. These 215 bridges in Idaho have been identified as vulnerable to scour damage.
| Bridge | State | Scour Status | Condition | Year Built | ADT |
|---|---|---|---|---|---|
| PORTNEUF RIVER | Idaho | Scour Critical — Unaddressed | Poor | 1962 | 1,200 |
| THORN CREEK | Idaho | Scour Critical — Unaddressed | Poor | 1955 | 360 |
| CANYON CREEK | Idaho | Scour Critical — Unaddressed | Poor | 2012 | 220 |
| SNAKE RIVER;SW BLISS BR | Idaho | Scour Critical — Unaddressed | Poor | 1977 | 190 |
| LAPWAI CREEK | Idaho | Scour Critical — Unaddressed | Poor | 1935 | 180 |
| HORNET CREEK | Idaho | Scour Critical — Unaddressed | Poor | 1949 | 100 |
| BIG CREEK TRESTLE | Idaho | Scour Critical — Unaddressed | Poor | 1912 | 100 |
| ROAD CREEK | Idaho | Scour Critical — Unaddressed | Poor | 2022 | 90 |
| JIM FORD CREEK | Idaho | Scour Critical — Unaddressed | Poor | 1965 | 80 |
| ST ANTHONY CANAL | Idaho | Scour Critical — Unaddressed | Poor | 1971 | 70 |
| SILVER CREEK | Idaho | Scour Critical — Unaddressed | Poor | 1978 | 60 |
| BLUE JOE CREEK | Idaho | Scour Critical — Unaddressed | Poor | 1953 | 50 |
| FRENCH CREEK | Idaho | Scour Critical — Unaddressed | Poor | 1957 | 50 |
| SELWAY RIVER-OHARA | Idaho | Scour Critical — Unaddressed | Poor | 1956 | 50 |
| EAST FORK FALL CREEK | Idaho | Scour Critical — Unaddressed | Poor | 2013 | 50 |
| BLACK WARRIOR CREEK | Idaho | Scour Critical — Unaddressed | Poor | 1975 | 30 |
| FALL CREEK | Idaho | Scour Critical — Unaddressed | Poor | 1987 | 30 |
| MIDDLE FORK BOISE RIVER | Idaho | Scour Critical — Unaddressed | Poor | 1957 | 20 |
| RAWSON CANAL | Idaho | Scour Critical — Countermeasures Ineffective | Good | 2024 | 3,300 |
| TRAIL CREEK | Idaho | Scour Critical — Countermeasures Ineffective | Fair | 1980 | 1,000 |
| BIG GULCH WASH #4 | Idaho | Scour Critical — Countermeasures Ineffective | Good | 2024 | 1,000 |
| BIG GULCH WASH #5 | Idaho | Scour Critical — Countermeasures Ineffective | Good | 2024 | 1,000 |
| S FK PALOUSE R(EDINGTON) | Idaho | Scour Critical — Countermeasures Ineffective | Good | 2024 | 300 |
| UPPER CROOKED RIVER | Idaho | Scour Critical — Countermeasures Ineffective | Good | 2024 | 110 |
| KNOWLTON CREEK | Idaho | Scour Critical — Countermeasures Ineffective | Good | 2024 | 100 |
| GOLD FORK RIVER | Idaho | Scour Critical — Countermeasures Ineffective | Fair | 1966 | 50 |
| GOLD FORK RIVER | Idaho | Scour Critical — Countermeasures Ineffective | Fair | 1966 | 50 |
| GRIMES CREEK | Idaho | Scour Critical — Countermeasures Ineffective | Good | 1982 | 12 |
| KENNALLY CREEK | Idaho | Scour Critical — Countermeasures Ineffective | Good | 1985 | 10 |
| SAND CREEK | Idaho | Scour Critical — Countermeasures Installed | Poor | 1994 | 27,500 |
| UPRR;INDIAN CR;CALDWELL | Idaho | Scour Critical — Countermeasures Installed | Fair | 1983 | 26,000 |
| SNAKE R;FRUITLAND BRIDGE | Idaho | Scour Critical — Countermeasures Installed | Good | 1967 | 24,500 |
| BOISE RIVER;N. CHANNEL | Idaho | Scour Critical — Countermeasures Installed | Good | 1992 | 22,000 |
| CLEARWATER RIVER;BNRR | Idaho | Scour Critical — Countermeasures Installed | Fair | 1951 | 21,000 |
| US 12;SNAKE RIVER | Idaho | Scour Critical — Countermeasures Installed | Fair | 1939 | 21,000 |
| PAYETTE RIVER | Idaho | Scour Critical — Countermeasures Installed | Fair | 1968 | 19,500 |
| SNAKE RIVER;W.BLACKFOOT | Idaho | Scour Critical — Countermeasures Installed | Fair | 1965 | 18,000 |
| SNAKE RIVER;HEYBURN BR. | Idaho | Scour Critical — Countermeasures Installed | Fair | 1977 | 17,000 |
| BOISE RIVER | Idaho | Scour Critical — Countermeasures Installed | Fair | 1931 | 16,500 |
| SNAKE RIVER;HEYBURN BR. | Idaho | Scour Critical — Countermeasures Installed | Fair | 1955 | 15,000 |
| KOOTENAI R;UPRR;BNNRS FY | Idaho | Scour Critical — Countermeasures Installed | Fair | 1984 | 13,000 |
| BLACKFOOT RIVER | Idaho | Scour Critical — Countermeasures Installed | Fair | 1962 | 12,500 |
| BLACKFOOT RIVER | Idaho | Scour Critical — Countermeasures Installed | Fair | 1962 | 12,500 |
| BOISE RIVER | Idaho | Scour Critical — Countermeasures Installed | Fair | 1994 | 12,000 |
| TETON CREEK | Idaho | Scour Critical — Countermeasures Installed | Fair | 1979 | 11,500 |
| SNAKE RIVER;HOMEDALE BR. | Idaho | Scour Critical — Countermeasures Installed | Fair | 1969 | 11,000 |
| S.FK.TETON RIVER | Idaho | Scour Critical — Countermeasures Installed | Fair | 1980 | 10,000 |
| S.FK.TETON RIVER | Idaho | Scour Critical — Countermeasures Installed | Fair | 1980 | 10,000 |
| RD;UPRR;SNAKE R;GLENNS F | Idaho | Scour Critical — Countermeasures Installed | Fair | 1974 | 9,750 |
| SNAKE RIVER;KING HILL | Idaho | Scour Critical — Countermeasures Installed | Fair | 1974 | 9,750 |
Scour Critical Rating Codes
| Code 2 — Unaddressed | Bridge is scour critical with no countermeasures installed. The foundation is vulnerable and no protective action has been taken. |
| Code 3 — Countermeasures Installed | Protective measures (riprap, sheet piling, etc.) have been installed to reduce scour risk, but the bridge remains classified as scour critical. |
| Code 6 — Countermeasures Ineffective | Protective measures were installed but have been assessed as ineffective. The bridge requires re-evaluation and additional action. |
About Scour Critical Bridges
Scour critical bridges have been identified through underwater inspection or analysis as having foundations that are unstable or could become unstable during flood conditions. FHWA requires action plans for all scour critical bridges. Famous scour failures include the 1987 Schoharie Creek Bridge collapse in New York.