County profile · official public datasets

Lake County, MT

117 public highway bridges tracked in the FHWA National Bridge Inventory: 57.3% rated Good, 27.4% Fair, 15.4% Poor.

117
Public bridges: 57.3%
Good condition: 15.4%
Poor condition

The verdict

According to the Federal Highway Administration's 2024 National Bridge Inventory.

Lake County pairs a higher-than-median Poor-condition share among rated counties in the state with a newer average build year than the state inventory.

52nd
of 56 on Poor share: 15.4%
Poor-condition share: 117
public highway bridges: 1995
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 #52 of 56 Montana counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 15.4%). Lake County, Montana contains 117 public highway bridges. Roughly 57.3% are rated “Good,” 27.4% “Fair,” and 15.4% “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.

Total bridges

117

Public highway bridges in Lake County

Good condition

57.3%

67 of 117 rated 7-9

Fair condition

27.4%

32 of 117 rated 5-6

Poor condition

15.4%

18 of 117 rated 4 or below

In-state Poor-share rank

#52 of 56

Among Montana counties with 5+ bridges, lower share ranks better

Condition distribution

Share of 117 NBI-tracked bridges by lowest applicable component rating.

Good

57.3% (67)

Fair

27.4% (32)

Poor

15.4% (18)

Lake County's Poor-condition bridges carry 12,161 vehicle crossings a day

That is 5% of the county's reported daily bridge traffic on 15.4% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 676 crossings a day against 2,502 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 117 of 117 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

17.9% of Lake County's bridges have passed the 50-year mark

21 of the 117 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 57.3% 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 58.2% of the county's Poor-condition bridge traffic

IRR - US 93 over NINE PIPE RESERVOIR, built 1933, carries 7,072 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 18-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 12,161 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1920s

2
1930s

4
1950s

4
1960s

10
1970s

9
1980s

9
1990s

6
2000s

39
2010s

25
2020s

9

What this shows Construction peaked in the 2000s, when 39 of the county's bridges still in the inventory were built, which is 33.3% of those with a recorded year. That cohort is now 15 to 24 years old in the 2024 inventory. Its average build year is 1995, 18 years newer than the Montana average of 1977.

How Lake County compares with Montana's closest counties by inventory size

The 5 Montana counties nearest Lake County in number of bridges, with their condition splits. Its 15.4% Poor share is the 6th-lowest of these 6. Its average build year of 1995 against a peer-group mean of 1976 is 19 years newer.

Showing the 5 closest of 55 Montana counties eligible for comparison.

Bridge inventory size and condition shares for Lake County and the 5 Montana counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Park County	124	21%	68.5%	10.5%	1976
Sanders County	120	40%	52.5%	7.5%	1979
Lake County (this page)	117	57.3%	27.4%	15.4%	1995
Rosebud County	114	18.4%	76.3%	5.3%	1973
Powell County	113	25.7%	68.1%	6.2%	1981
Dawson County	109	8.3%	85.3%	6.4%	1972

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 Montana so the neighborhoods are not the same-state size table above.

Similar inventory size

Nearest county inventories outside MT (117 bridges here).

Franklin County, GA · 117 bridges
Polk County, GA · 117 bridges
Clark County, KY · 117 bridges
Fleming County, KY · 117 bridges

Similar average build year

Nearest mean year-built outside MT (1995 here).

Williamson County, TX · avg 1995 · 1,170 bridges
Craighead County, AR · avg 1995 · 442 bridges
Utah County, UT · avg 1995 · 271 bridges
DeSoto County, MS · avg 1995 · 266 bridges

Source: FHWA National Bridge Inventory, 2024 release. Peers floor at 10 bridges so stub inventories cannot own the match.

All 117 Good 67 Fair 32 Poor 18

All bridges (117)

Sort:

Lake County Bridge Snapshot

Condition distribution

Lake County's Poor-condition bridges carry 12,161 vehicle crossings a day

17.9% of Lake County's bridges have passed the 50-year mark

One structure carries 58.2% of the county's Poor-condition bridge traffic

How Lake County compares with Montana's closest counties by inventory size

Nationwide counties with similar inventory size or average build year

Similar inventory size

Similar average build year

All bridges (117)

YENNE POINT RD

DELANEY WAY

GLOVER RD

KOPP RD

FISH HATCHERY RD

IRR - US 93

TERRACE LAKE RD

TERRACE LAKE RD

JOCKO CANYON RD

N VALLEY CREEK RD

IRR - US 93

IRR - US 93

OLD US HWY 93

S 83 FH 15

BEAVERHEAD DR

IRR - S 212

EMORY RD

IRR - S 200

N VALLEY CREEK RD

N CROW RD

S FERNDALE DR

THERESA ADAMS LN

US 93

US 93

S 83 FH 15

US 93

FOREST ROAD

OLD US HWY 93

US 93

US 93

JOCKO CANYON ROAD

EAGLE PASS TRAIL

US 93

Foothill Road

MOLLMAN PASS TRAIL

HILLSIDE ROAD

GARCON GULCH ROAD

SKYLINE DR

OLD FREIGHT ROAD

MCDONALD LAKE RD

NO DATA ENTERED

SKYLINE DR

LEIGHTON RD

OLD FREIGHT RD

FORD RD

JOCKO CANYON RD

NFSR

BUFFALO BRIDGE RD

SKYLINE DR

TIMBERLANE RD

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