Total bridges
129
Public highway bridges in Lake County
County profile · official public datasets
Lake County, CA
129 public highway bridges tracked in the FHWA National Bridge Inventory: 30.2% rated Good, 62% Fair, 7.8% Poor.
- 129
- Public bridges
- 30.2%
- Good condition
- 7.8%
- Poor condition
The verdict
According to the Federal Highway Administration's 2024 National Bridge Inventory.
Lake County posts a higher-than-median Poor-condition share among rated counties in the state across mid-size county bridge inventory.
- 37th
- of 58 on Poor share
- 7.8%
- Poor-condition share
- 129
- public highway bridges
- 1970
- avg year built
Poor is an FHWA condition category from the lowest applicable component rating (4 or below), not a live crossing-safety or closure decision. Rankings cover counties with at least five public highway bridges.
Lake County Bridge Snapshot
According to the Federal Highway Administration's 2024 National Bridge Inventory, Lake County ranks #37 of 58 California counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 7.8%). Lake County, California contains 129 public highway bridges. Roughly 30.2% are rated “Good,” 62% “Fair,” and 7.8% “Poor.” Poor means the lowest applicable deck, superstructure, substructure, or culvert rating is 4 or below on the 0–9 NBI scale. It is a condition category, not a live safety or closure decision.
Responsible agencies inspect covered bridges on risk-based intervals under current NBIS rules and submit inventory data to FHWA annually. The list below shows every NBI-tracked bridge in the county. Use the “Sort by” controls to change the ordering, and click any row for its reported inspection date, traffic count, and condition fields.
Source: FHWA National Bridge Inventory. See methodology for full definitions.
Good condition
30.2%
39 of 129 rated 7-9
Fair condition
62%
80 of 129 rated 5-6
Poor condition
7.8%
10 of 129 rated 4 or below
In-state Poor-share rank
#37 of 58
Among California counties with 5+ bridges, lower share ranks better
Condition distribution
Share of 129 NBI-tracked bridges by lowest applicable component rating.
Good 30.2% (39)
Fair 62% (80)
Poor 7.8% (10)
Lake County's Poor-condition bridges carry 1,538 vehicle crossings a day
That is 0.5% of the county's reported daily bridge traffic on 7.8% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 154 crossings a day against 3,412 for a Good-condition one. A Poor rating is a condition category, not a closure or a live safety judgement; it means the lowest applicable component rating is 4 or below.
Computed over the 129 of 129 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.
69.8% of Lake County's bridges have passed the 50-year mark
90 of the 129 bridges with a recorded construction year were built in 1974 or earlier. Age alone is not a defect: a well-maintained older bridge can rate Good, and 30.2% of this county's inventory does. Even so, this older cohort is the population from which future Poor ratings are drawn, which is why the age profile below matters alongside the condition split above.
Cutoff derives from the 2024 release year minus a 50-year design life. Source: FHWA National Bridge Inventory, 2024 release.
One structure carries 22.8% of the county's Poor-condition bridge traffic
ROAD M1 over EEL RIVER, built 1971, carries 350 vehicles a day, the most of any Poor-rated structure here. The county's Poor-condition exposure is concentrated rather than evenly spread, so the 10-bridge count understates how much of the daily burden sits on a single crossing.
Share is of the 1,538 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.
When Lake County's bridges were built
129 bridges with a recorded construction year, grouped by decade
- 1900s 1
1900–1909
1 bridges
- 1920s 2
1920–1929
2 bridges
- 1930s 11
1930–1939
11 bridges
- 1940s 8
1940–1949
8 bridges
- 1950s
1950–1959
16 bridges
- 1960s
1960–1969
33 bridges
- 1970s
1970–1979
23 bridges
- 1980s 10
1980–1989
10 bridges
- 1990s 8
1990–1999
8 bridges
- 2000s 5
2000–2009
5 bridges
- 2010s 10
2010–2019
10 bridges
- 2020s 2
2020–2029
2 bridges
What this shows Construction peaked in the 1960s, when 33 of the county's bridges still in the inventory were built, which is 25.6% of those with a recorded year. That cohort is now 55 to 64 years old in the 2024 inventory. Its average build year (1970) matches the California average (1970).
How Lake County compares with California's closest counties by inventory size
The 5 California counties nearest Lake County in number of bridges, with their condition splits. Its 7.8% Poor share is the 3rd-lowest of these 6. Its average build year of 1970 against a peer-group mean of 1968 is in line with the group.
Showing the 5 closest of 57 California counties eligible for comparison.
| County | Bridges | Good | Fair | Poor | Avg. built |
|---|---|---|---|---|---|
| San Francisco County | 143 | 34.3% | 51% | 14.7% | 1969 |
| Nevada County | 135 | 45.2% | 40.7% | 14.1% | 1972 |
| Lake County (this page) | 129 | 30.2% | 62% | 7.8% | 1970 |
| Yuba County | 127 | 37.8% | 55.9% | 6.3% | 1967 |
| Tuolumne County | 125 | 36% | 56.8% | 7.2% | 1964 |
| Sutter County | 121 | 33.9% | 52.9% | 13.2% | 1968 |
Each share is of that county's own total tracked bridges; peers are the counties with 5 or more bridges whose inventory size is closest to Lake County's. Source: FHWA National Bridge Inventory, 2024 release.
Nationwide counties with similar inventory size or average build year
Two NBI-derived peer sets for Lake County, both outside California so the neighborhoods are not the same-state size table above.
Similar inventory size
Nearest county inventories outside CA (129 bridges here).
- Clay County, AL · 129 bridges
- Cross County, AR · 129 bridges
- Lincoln County, CO · 129 bridges
- Martin County, FL · 129 bridges
Similar average build year
Nearest mean year-built outside CA (1970 here).
- Hamilton County, OH · avg 1970 · 783 bridges
- Yavapai County, AZ · avg 1970 · 543 bridges
- Garfield County, OK · avg 1970 · 504 bridges
- Somerset County, NJ · avg 1970 · 397 bridges
Source: FHWA National Bridge Inventory, 2024 release. Peers floor at 10 bridges so stub inventories cannot own the match.
Poor-condition bridges (10)
ROAD M1
PoorOver: EEL RIVER
13 MILES NE POTTER VALLEY, Lake, CA
Built 1971 ADT: 350
S COW MTN -8 MILE
PoorOver: Panther Creek
11.4 miles SE of Ukiah, Lake, CA
Built 2000 Load: 6.5 t ADT: 25
CHALK MTN RD
PoorOver: NORTH FORK CACHE CREEK
IN SPRING VALLEY LAKE DEV, Lake, CA
Built 1967 Load: 8.7 t ADT: 15
34013: HUNTING CRE
PoorOver: HUNTING CREEK
20.4 mi W of Lower Lake, Lake, CA
Built 2003 Load: 13.0 t ADT: 25
WOLF CREEK ROAD
PoorOver: WOLF CREEK
IN SPRING VALLEY LAKE DEV, Lake, CA
Built 1967 Load: 16.5 t ADT: 26
BARTLETT SPRNGS RD
PoorOver: BARTLETT CREEK
19 MI E OF SR 20, Lake, CA
Built 1950 Load: 33.0 t ADT: 108
BIG CANYON ROAD
PoorOver: BIG CANYON CREEK
8 1/4 MI N OF SR 175, Lake, CA
Built 1930 Load: 35.6 t ADT: 304
BIG CANYON ROAD
PoorOver: BIG CANYON CREEK
8 MI N OF SR 175, Lake, CA
Built 1930 Load: 36.0 t ADT: 308
ELK MOUNTAIN RD
PoorOver: SODA CREEK
SIMMONS RD IN HULLVILLE, Lake, CA
Built 1979 Load: 37.6 t ADT: 169
BIG CANYON RD
PoorOver: BIG CANYON CREEK
10 MI N OF SR 175, Lake, CA
Built 1956 Load: 43.4 t ADT: 208
Read our methodology - how this data is sourced, computed, and verified.
Related
Data sourced from official public datasets. See our methodology for details. Retrieved and formatted by PlainBridges
Every figure on PlainBridges is rendered directly from federal source data, no number is typed in by an editor. This page draws directly on federal source data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. NBI condition categories reflect the latest reported inventory record, not a live safety, closure, or travel decision.