Siskiyou County, CA

423 public highway bridges

Siskiyou County Bridge Snapshot

Siskiyou County, California contains 423 public highway bridges in the FHWA National Bridge Inventory. Roughly 36.2% are rated “Good,” 49.6% “Fair,” 5.4% “Poor,” and 5.4% are classified as structurally deficient — the federal designation for spans whose deck, superstructure, or substructure has been rated 4 or below on the 0–9 NBI scale. Structurally deficient does not mean unsafe to cross; it means the bridge is on the priority list for repair or replacement.

Inspections in CA are conducted by certified engineers from the state Department of Transportation on a 24-month cycle, and results are reported back to the FHWA each spring. The list below shows every NBI-tracked bridge in the county, sorted by inventory load rating. Use the “Sort by” controls to surface the lowest-rated spans first, and click any row for full inspection history, traffic counts, and condition trends.

Source: FHWA National Bridge Inventory. See methodology for full definitions.

423

Total Bridges

36.2%

Good

5.4%

Poor

5.4%

Structurally Deficient

Condition Distribution

Good

36.2% (153)

Fair

49.6% (210)

Poor

5.4% (23)

SD

5.4% (23)

All Bridges (423)

Sort:

INTERSTATE 5

Over: CRAM GULCH

02-SIS-005-R39.02, Siskiyou, CA

Built 1969 Load: 37.6 t ADT: 7,850

INTERSTATE 5 NB

Over: SISKIYOU WAY

02-SIS-005-R18.71-WEED, Siskiyou, CA

Built 1973 Load: 37.6 t ADT: 7,150

COTTONWOOD CR RD

Over: DITCH CREEK

0.25 MI N/O DITCH CRK RD, Siskiyou, CA

Built 1968 Load: 38.2 t ADT: 95

MOFFETT CREEK RD

Over: MOFFETT CREEK

4.4 MI E SR 3, Siskiyou, CA

Built 1975 Load: 38.6 t ADT: 145

AGER RD

Over: BLACK MOUNTAIN GULCH

7.6 MI NORTH SR 3, Siskiyou, CA

Built 1980 Load: 38.9 t ADT: 648

INTERSTATE 5 NB

Over: UP RR & AMTRAK

02-SIS-005-R15.94, Siskiyou, CA

Built 1973 Load: 39.2 t ADT: 12,750

INTERSTATE 5

Over: GUYS GULCH

02-SIS-005-R39.27, Siskiyou, CA

Built 1969 Load: 39.9 t ADT: 8,300

SOUTH FORK ROAD

Over: SOUTH FORK SCOTT RIVER

E/O CECILVILLE ROAD, Siskiyou, CA

Built 1969 Load: 40.2 t ADT: 49

QUARTZ VALLEY ROAD

Over: SHACKLEFORD CREEK

3.6 MI S SCOTT RIVER RD, Siskiyou, CA

Built 1967 Load: 40.5 t ADT: 330

STATE ROUTE 3

Over: EAST FORK SCOTT RIVER

02-SIS-003-6.90, Siskiyou, CA

Built 1968 Load: 41.1 t ADT: 190

STATE ROUTE 96

Over: KLAMATH RIVER

02-SIS-096-R15.61, Siskiyou, CA

Built 1967 Load: 41.5 t ADT: 330

HAWKINSVLE HUMB RD

Over: HUMBUG CREEK

SOUTH HUMBUG CREEK RD, Siskiyou, CA

Built 1971 Load: 41.5 t ADT: 20

BEAVER CREEK ROAD

Over: BEAVER CREEK

BEAVER, Siskiyou, CA

Built 1963 Load: 42.8 t ADT: 50

INTERSTATE 5 NB

Over: UP RR & AMTRAK

02-SIS-005-R9.20, Siskiyou, CA

Built 1964 Load: 43.7 t ADT: 20,000

STATE ROUTE 3

Over: WILDCAT CREEK

02-SIS-003-9.75, Siskiyou, CA

Built 1958 Load: 43.7 t ADT: 925

SERPA LANE

Over: KIDDER CREEK

0.45 MI E OF SR 3, Siskiyou, CA

Built 1967 Load: 44.4 t ADT: 164

STATE ROUTE 3

Over: MILL CREEK

02-SIS-003-6.82, Siskiyou, CA

Built 1970 Load: 45.4 t ADT: 190

STATE ROUTE 3

Over: SOUTH FORK SCOTT RIVER

02-SIS-003-8.89, Siskiyou, CA

Built 1958 Load: 46.0 t ADT: 345

GAZELLE-CALLAHAN R

Over: NOYES VALLEY CREEK

0.1 MI N MASTERSON RD, Siskiyou, CA

Built 1972 Load: 46.0 t ADT: 287

FRENCH CREEK RD

Over: FRENCH CREEK

5.2 MI S OF S.H. 3, Siskiyou, CA

Built 1990 Load: 46.3 t ADT: 20

CECILVILLE ROAD

Over: MCNEAL CREEK

1 MI S/O SALMON RIVER RD, Siskiyou, CA

Built 1937 Load: 46.7 t ADT: 101

INTERSTATE 5 SB

Over: SISKIYOU WAY

02-SIS-005-R18.71-WEED, Siskiyou, CA

Built 1973 Load: 47.3 t ADT: 7,150

CARIBOU ROAD

Over: RAYS GULCH

4.7 MI S/O CECILVILLE RD, Siskiyou, CA

Built 1982 Load: 47.3 t ADT: 29

INTERSTATE 5 NB

Over: HUTTON CREEK

02-SIS-005-R64.82R, Siskiyou, CA

Built 1974 Load: 47.6 t ADT: 15,300

INTERSTATE 5 NB

Over: COTTONWOOD CREEK

02-SIS-005-R63.65R, Siskiyou, CA

Built 1974 Load: 48.3 t ADT: 15,300

DOOLITTLE CREEK RD

Over: INDIAN CREEK

AT INDIAN CREEK RD, Siskiyou, CA

Built 1965 Load: 48.6 t ADT: 79

MCADAMS CREEK RD

Over: MOFFETT CREEK

0.25 MI N SR 3, Siskiyou, CA

Built 1978 Load: 52.8 t ADT: 256

CECILVILLE ROAD

Over: NORTH FORK SALMON RIVER

S/O SALMON RIVER ROAD, Siskiyou, CA

Built 1985 Load: 54.4 t ADT: 116

EAST-WEST RD

Over: LOST RIVER

1.8 MI W SR 139, Siskiyou, CA

Built 1984 Load: 54.4 t ADT: 827

GRIDER ROAD

Over: GRIDER CREEK

2.7 MI S SR 96, Siskiyou, CA

Built 1976 Load: 54.4 t ADT: 94

FRENCH CR RD

Over: FRENCH CREEK

3.7 MI S SR 3, Siskiyou, CA

Built 1986 Load: 54.4 t ADT: 245

INTERSTATE 5 SB

Over: COTTONWOOD CREEK

02-SIS-005-R63.77L, Siskiyou, CA

Built 1974 Load: 55.1 t ADT: 7,300

CURLY JACK ROAD

Over: ELK CREEK

0.8 MI S OF ELK CREEK RD, Siskiyou, CA

Built 1975 Load: 55.4 t ADT: 624

ANDERSON GRADE RD

Over: YREKA CREEK

0.1 MI E OF SR 263, Siskiyou, CA

Built 1971 Load: 56.7 t ADT: 90

ISLAND ROAD

Over: SCOTT RIVER OVERFLOW

0.5 MI E HOLZHAUSER LANE, Siskiyou, CA

Built 1977 Load: 57.0 t ADT: 158

ISLAND ROAD

Over: SCOTT RIVER OVERFLOW

0.2 MI W OF EASTSIDE RD, Siskiyou, CA

Built 1977 Load: 57.3 t ADT: 161

ISLAND ROAD

Over: SCOTT RIVER OVERFLOW

0.1 MI W OF ISLAND RD, Siskiyou, CA

Built 1977 Load: 58.3 t ADT: 86

EDGEWOOD ROAD

Over: SHASTA RIVER

0.1 MI W OL EDGEWOOD WEED, Siskiyou, CA

Built 1973 Load: 59.9 t ADT: 395

CARIBOU ROAD

Over: SOUTH FORK SALMON RIVER

4 MI S/O CECILVILLE ROAD, Siskiyou, CA

Built 1984 Load: 64.8 t ADT: 48

TENNANT RD

Over: ANTELOPE CREEK

11.6 MI SE SR97, Siskiyou, CA

Built 1971 Load: 66.4 t ADT: 79

SAWYERS BAR RD

Over: NORTH FORK SALMON RIVER

3 MI N WHITES GULCH RD, Siskiyou, CA

Built 1982 Load: 68.0 t ADT: 105

MCADAMS CREEK RD

Over: MCADAMS CREEK

2.55 MI N SR 3, Siskiyou, CA

Built 1975 Load: 73.9 t ADT: 256

SLOUGH RD

Over: LOWER PARKS CREEK

4.1 MI S OF LOUIE RD, Siskiyou, CA

Built 1975 Load: 76.8 t ADT: 7

CECILVILLE ROAD

Over: SOUTH FORK SALMON RIVER

0.1 MI S/O SALMON RIVER R, Siskiyou, CA

Built 1986 Load: 78.1 t ADT: 116

FISH LAKE ROAD

Over: E. FORK SALMON RIVER

CALLAHAN, Siskiyou, CA

Built 1966 Load: 90.8 t ADT: 15

WRIGHTS LAKE ROAD

Over: BOULDER CREEK

SCOTT BAR, Siskiyou, CA

Built 1967 Load: 90.8 t ADT: 50

INTERSTATE 5

Over: LITTLE CASTLE CREEK

02-SIS-005-0.04, Siskiyou, CA

Built 1960 Load: 99.9 t ADT: 18,000

YREKA HEADQUARTERS

Over: YREKA CREEK

GUNSIGHT, Siskiyou, CA

Built 1975 ADT: 50

MCKINNEY CREEK RD

Over: MCKINNEY CREEK

GUNSIGHT, Siskiyou, CA

Built 1976 ADT: 50

WEST BEAVER ROAD

Over: JAYNES CANYON

BEAVER, Siskiyou, CA

Built 1976 ADT: 50

Read our methodology — how this data is sourced, computed, and verified.

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Data sourced from official U.S. government datasets. See our methodology for details. Retrieved and formatted by PlainBridges Editorial

Reviewed byPlainbridges Editorial, Plain Bridges Editorial Team · June 6, 2026