Scour Critical Bridges in Iowa

392 bridges in Iowa 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 392 bridges in Iowa have been identified as vulnerable to scour damage.

Clear
Bridge State Scour Status Condition Year Built ADT
SMALL STREAM Iowa Scour Critical — Unaddressed Poor 1956 110
STREAM Iowa Scour Critical — Unaddressed Poor 1925 11
DRAINAGE Iowa Scour Critical — Unaddressed Poor 1930 9
DRAINAGE Iowa Scour Critical — Countermeasures Ineffective Fair 1948 11,400
SINK CREEK Iowa Scour Critical — Countermeasures Ineffective Good 2022 4,173
SMALL Iowa Scour Critical — Countermeasures Ineffective Good 2023 104
SPRING CREEK Iowa Scour Critical — Countermeasures Ineffective Fair 1946 5
MISS RVR RR & IA 461 Iowa Scour Critical — Countermeasures Installed Poor 1940 26,500
CEDAR RIVER Iowa Scour Critical — Countermeasures Installed Fair 1920 13,000
RACCOON R & TRAIL Iowa Scour Critical — Countermeasures Installed Fair 1915 7,253
PERRY CREEK Iowa Scour Critical — Countermeasures Installed Fair 1978 6,129
MUSCATINE SLOUGH Iowa Scour Critical — Countermeasures Installed Good 2002 3,500
MUSCATINE SLOUGH Iowa Scour Critical — Countermeasures Installed Good 2002 3,500
PERRY CREEK Iowa Scour Critical — Countermeasures Installed Fair 1950 1,675
NISHNABOTNA RIVER Iowa Scour Critical — Countermeasures Installed Poor 1961 1,524
WALNUT CREEK Iowa Scour Critical — Countermeasures Installed Fair 1938 1,180
RACCOON RIVER Iowa Scour Critical — Countermeasures Installed Fair 1912 916
DRAINAGE Iowa Scour Critical — Countermeasures Installed Fair 1962 783
SMALL NATURAL STREAM Iowa Scour Critical — Countermeasures Installed Poor 1940 649
MUDDY CREEK Iowa Scour Critical — Countermeasures Installed Poor 1967 628
BRANCH BEAVER CREEK Iowa Scour Critical — Countermeasures Installed Poor 1968 619
RED OAK CREEK Iowa Scour Critical — Countermeasures Installed Fair 1964 571
MUD CREEK Iowa Scour Critical — Countermeasures Installed Poor 1961 509
BROOKS CREEK Iowa Scour Critical — Countermeasures Installed Poor 1966 509
STREAM Iowa Scour Critical — Countermeasures Installed Poor 1966 480
DRAINAGE DITCH Iowa Scour Critical — Countermeasures Installed Poor 1914 459
SPRING CREEK Iowa Scour Critical — Countermeasures Installed Poor 1959 430
WELDON RIVER Iowa Scour Critical — Countermeasures Installed Poor 1958 379
BIG CREEK Iowa Scour Critical — Countermeasures Installed Poor 1962 369
SMALL STREAM Iowa Scour Critical — Countermeasures Installed Fair 1956 342
EAST NISHNABOTNA Iowa Scour Critical — Countermeasures Installed Fair 1959 329
DRAINAGE Iowa Scour Critical — Countermeasures Installed Fair 1957 320
KLONDIKE CREEK Iowa Scour Critical — Countermeasures Installed Poor 1966 309
EAST BOYER RIVER Iowa Scour Critical — Countermeasures Installed Poor 1913 303
BRANCH OTTER CREEK Iowa Scour Critical — Countermeasures Installed Poor 1970 288
STREAM Iowa Scour Critical — Countermeasures Installed Poor 1981 270
BIG CREEK Iowa Scour Critical — Countermeasures Installed Poor 1964 270
W FORK GRAND RIVER Iowa Scour Critical — Countermeasures Installed Poor 1956 219
SHELL ROCK RIV OVERFLOW Iowa Scour Critical — Countermeasures Installed Poor 1992 207
SHELL ROCK RIV OVERFLOW Iowa Scour Critical — Countermeasures Installed Fair 1992 207
LITTLE CEDAR Iowa Scour Critical — Countermeasures Installed Poor 1965 196
DRAINAGE Iowa Scour Critical — Countermeasures Installed Poor 1975 180
EAGLE CREEK Iowa Scour Critical — Countermeasures Installed Fair 1981 170
STREAM Iowa Scour Critical — Countermeasures Installed Poor 1930 160
CRANE CREEK Iowa Scour Critical — Countermeasures Installed Poor 1959 157
LAMALEES CREEK Iowa Scour Critical — Countermeasures Installed Poor 1957 150
SM STREAM Iowa Scour Critical — Countermeasures Installed Fair 1973 140
NISHNABOTNA RIVER Iowa Scour Critical — Countermeasures Installed Fair 1972 133
PLUM CREEK Iowa Scour Critical — Countermeasures Installed Poor 1954 120
UPPER IOWA RIVER BRANCH Iowa Scour Critical — Countermeasures Installed Fair 1971 118

Scour Critical Rating Codes

Code 2 — UnaddressedBridge is scour critical with no countermeasures installed. The foundation is vulnerable and no protective action has been taken.
Code 3 — Countermeasures InstalledProtective measures (riprap, sheet piling, etc.) have been installed to reduce scour risk, but the bridge remains classified as scour critical.
Code 6 — Countermeasures IneffectiveProtective 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.