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:

CORP RR

Over: INTERSTATE 5

02-SIS-005-R66.97, Siskiyou, CA

Built 1971 ADT: 15,300

REAM AVE

Over: INTERSTATE 5

02-SIS-005-R9.65-MSHA, Siskiyou, CA

Built 1964 ADT: 20,000

LAKE ST

Over: INTERSTATE 5

02-SIS-005-R10.48-MSHA, Siskiyou, CA

Built 1964 ADT: 20,600

UP RR & AMTRAK

Over: INTERSTATE 5

02-SIS-005-R12.02, Siskiyou, CA

Built 1963 ADT: 20,000

LASSEN LANE

Over: INTERSTATE 5

02-SIS-005-R11.17-MSHA, Siskiyou, CA

Built 1964 ADT: 20,000

S5-N MT SHASTA OFF

Over: INTERSTATE 5

02-SIS-005-R12.06, Siskiyou, CA

Built 1964 ADT: 20,600

SISKIYOU AVE

Over: INTERSTATE 5

02-SIS-005-2.92-DMR, Siskiyou, CA

Built 1966 ADT: 2,000

AZALEA ROAD

Over: INTERSTATE 5

02-SIS-005-R8.29, Siskiyou, CA

Built 1964 ADT: 20,700

S5-S89 & N89-S5 CN

Over: INTERSTATE 5

02-SIS-089-R34.60, Siskiyou, CA

Built 1964 ADT: 19,300

S MT SHASTA-S5 ON

Over: INTERSTATE 5

02-SIS-005-R8.79, Siskiyou, CA

Built 1964 ADT: 19,300

I 5 SB

Over: E96-N5 CON,KLAMATH RIVER

02-SIS-005-R58.18L, Siskiyou, CA

Built 1969 ADT: 255

I 5 NB

Over: E96-N5 CON,KLAMATH RIVER

02-SIS-005-R58.18R, Siskiyou, CA

Built 1969 ADT: 255

INTERSTATE 5

Over: STEWART SPRINGS ROAD

02-SIS-005-R23.00, Siskiyou, CA

Built 1969 ADT: 100

INTERSTATE 5

Over: STEWART SPRINGS ROAD

02-SIS-005-R23.00, Siskiyou, CA

Built 1969 ADT: 100

LOUIE ROAD

Over: INTERSTATE 5

02-SIS-005-R31.18, Siskiyou, CA

Built 1969 ADT: 14,800

INTERSTATE 5 SB

Over: OBERLIN ROAD

02-SIS-005-R46.49-YRE, Siskiyou, CA

Built 1970 ADT: 4,000

INTERSTATE 5 NB

Over: OBERLIN ROAD

02-SIS-005-R46.49-YRE, Siskiyou, CA

Built 1970 ADT: 4,000

99-97 CUTOFF

Over: INTERSTATE 5

02-SIS-005-R38.21, Siskiyou, CA

Built 1969 ADT: 15,700

WALTERS ROAD

Over: INTERSTATE 5

02-SIS-005-R44.31, Siskiyou, CA

Built 1970 ADT: 17,100

INTERSTATE 5 SB

Over: STATE ROUTE 3

02-SIS-005-R48.23-YRE, Siskiyou, CA

Built 1970 ADT: 3,450

INTERSTATE 5 NB

Over: STATE ROUTE 3

02-SIS-005-R48.23-YRE, Siskiyou, CA

Built 1970 ADT: 3,450

ABRAMS LAKE ROAD

Over: INTERSTATE 5 SB

02-SIS-005-R13.18L, Siskiyou, CA

Built 1973 ADT: 24,600

ABRAMS LAKE ROAD

Over: INTERSTATE 5 NB

02-SIS-005-R13.18R, Siskiyou, CA

Built 1973 ADT: 22,500

INTERSTATE 5

Over: KILLGORE HILLS ROAD

02-SIS-005-R42.51, Siskiyou, CA

Built 1970 ADT: 2,530

INTERSTATE 5

Over: KILLGORE HILLS ROAD

02-SIS-005-R42.51, Siskiyou, CA

Built 1970 ADT: 2,530

SLOUGH ROAD

Over: INTERSTATE 5

02-SIS-005-R34.96, Siskiyou, CA

Built 1969 ADT: 15,700

INTERSTATE 5 SB

Over: MINER STREET

02-SIS-005-R47.56-YRE, Siskiyou, CA

Built 1970 ADT: 2,640

ROUTE 5

Over: MINER STREET

02-SIS-005-R47.56-YRE, Siskiyou, CA

Built 1970 ADT: 2,640

INTERSTATE 5 SB

Over: STATE ROUTE 265

02-SIS-005-R19.85-WEED, Siskiyou, CA

Built 1973 ADT: 2,000

INTERSTATE 5 NB

Over: STATE ROUTE 265

02-SIS-005-R19.85-WEED, Siskiyou, CA

Built 1973 ADT: 1,800

INTERSTATE 5 SB

Over: STATE ROUTE 97

02-SIS-005-R19.05-WEED, Siskiyou, CA

Built 1973 ADT: 12,100

INTERSTATE 5 NB

Over: STATE ROUTE 97

02-SIS-005-R19.05-WEED, Siskiyou, CA

Built 1973 ADT: 12,100

DITCH CREEK ROAD

Over: INTERSTATE 5

02-SIS-005-R62.92, Siskiyou, CA

Built 1974 ADT: 15,300

BAILEY HILL ROAD

Over: INTERSTATE 5

02-SIS-005-R65.52R, Siskiyou, CA

Built 1974 ADT: 15,300

INTERSTATE 5 SB

Over: HENLEY WAY

02-SIS-005-R61.55, Siskiyou, CA

Built 1974 ADT: 1,000

INTERSTATE 5 NB

Over: HENLEY WAY

02-SIS-005-R61.55, Siskiyou, CA

Built 1974 ADT: 1,020

HILT ROAD

Over: INTERSTATE 5

02-SIS-005-R68.33, Siskiyou, CA

Built 2017 ADT: 15,100

HORSE CREEK ROAD

Over: HORSE CREEK

HORSE, Siskiyou, CA

Built 1959 ADT: 50

SEIAD CREEK ROAD

Over: SEIAD CREEK

HORSE, Siskiyou, CA

Built 1959 ADT: 50

NO DATA ENTERED

Over: BEAR CREEK

BEAVER, Siskiyou, CA

Built 1990 ADT: 5

NO DATA ENTERED

Over: BEAR CREEK

BEAVER, Siskiyou, CA

Built 1969 ADT: 5

SOUTH INDIAN ROAD

Over: S. FORK INDIAN CREEK

INDIAN, Siskiyou, CA

Built 1966 ADT: 50

BENJAMIN CREEK RD

Over: DOOLITTLE CREEK

CLEAR CREEK, Siskiyou, CA

Built 1975 ADT: 50

ELK CREEK ROAD

Over: ELK CREEK

ELK-THOMPSON, Siskiyou, CA

Built 1949 ADT: 50

NO DATA ENTERED

Over: DOOLITTLE CREEK

ELK-THOMPSON, Siskiyou, CA

Built 1972 ADT: 10

NO DATA ENTERED

Over: TAYLOR CREEK

CECILVILLE, Siskiyou, CA

Built 1967 ADT: 10

NO DATA ENTERED

Over: WEST FK SHADOW CREEK

CECILVILLE, Siskiyou, CA

Built 1991 ADT: 5

NO DATA ENTERED

Over: TAYLOR CREEK

CECILVILLE, Siskiyou, CA

Built 1965 ADT: 30

CHINA MT. ROAD

Over: CRATER CREEK

CALLAHAN, Siskiyou, CA

Built 1974 ADT: 50

TWO POINTS ROAD

Over: SINGLETON CREEK

SCOTT BAR, Siskiyou, CA

Built 1996 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