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Buying land in Franklin County, Idaho: what to check

Franklin County covers 663 square miles of land and 5 of water in Idaho, with about 15,638 residents in 2024 (up 10.2% since 2020). The 2020 Census counted 100% of its land as rural and 0% of residents as living in urban areas. Farms operate 65% of the county's land. Below: how much of Franklin County floods, what its soils allow, what farmland is worth and how often it's in drought, from free public data with every source linked.

Check a location in Franklin CountySee a sample report

Franklin County at a glance

In the 100-year floodplain

2.1%

Above the state's county median (1.3%)

FEMA National Risk Index

Hydric (wetland-type) soils

1.6%

About the state's county median (1.6%)

USDA NRCS Web Soil Survey (SSURGO)

Soils very limited for septic

95%

USDA NRCS Web Soil Survey (SSURGO)

Farm land value, 2022

$3,278/acre

Below the state's county median ($3,845)

USDA NASS, 2022 Census of Agriculture

Weeks in severe drought

42%

Share of weekly maps, 2021–2026

U.S. Drought Monitor county statistics

Land classed rural

100%

Census 2020 Census urban and rural classification

What to check before buying land in Franklin County

Ordered by what Franklin County's numbers point to. Every parcel differs, so treat this as where to look first.

  1. 1.Budget for a perc test and maybe an engineered septic

    USDA rates 95% of Franklin County's mapped soils "very limited" for conventional septic absorption fields and 0% "not limited".

    Without city sewer you need a septic permit from the county or state health department. Make the offer contingent on a passing soil or perc test; mound and aerobic systems can cost several times a conventional one.

    Guide: Perc tests and septic systems

  2. 2.Check slope where you'd build and where the driveway goes

    67% of Franklin County's mapped soils have an average slope over 15% (USDA SSURGO).

    Steep ground means grading, retaining walls, longer driveways and erosion control. Compare the slope at the house site and along the access route, not just the parcel average.

    Guide: Terrain and slope

  3. 3.Prove the water supply before you buy

    At least half of Franklin County was in severe drought (D2) or worse in 42% of the 262 weekly U.S. Drought Monitor maps from 2021 to 2026. Idaho allocates water by permit or water right, so a well or pond isn't automatic.

    Ask whether the land has a public water connection, an existing well (and its log and yield), or neighbors' well depths from the state well database. For a new well, check permits and typical depth with the state agency first.

    Guide: Wells, public water and water rights

  4. 4.Confirm legal road access and power

    The 2020 Census classified 100% of Franklin County's land area as rural.

    Rural tracts are often sold without recorded access or a power line nearby. Get the title company to confirm a recorded easement or public road frontage, and ask the electric co-op what a line extension costs.

    Guide: Road access and landlocked land

  5. 5.Confirm the flood zone at your exact spot

    2.1% of the county's area is in the 1%-annual-chance (100-year) floodplain FEMA's National Risk Index uses for inland flooding; 1.1% of its mapped soils flood occasionally or frequently.

    Even where little of the county floods, creeks and low spots do. Check the FEMA zone at the building site and the driveway route.

    Guide: Flood zones before buying land

  6. 6.Sanity-check the price per acre

    Farm real estate in Franklin County averaged $3,278 an acre including buildings in the 2022 Census of Agriculture, and 6% of its mapped soils are prime or of statewide importance.

    Compare the asking price with recent sales of similar tracts, not the county average, which mixes cropland, pasture, timber and homesites. If an ag tax valuation applies, ask what the rollback taxes would be if you change the use.

    Guide: Land due diligence checklist

Flood zones, wetlands and water in Franklin County

Area in the 1%-annual-chance (100-year) floodplain
2.1%, 14th highest of 44 in Idaho FEMA National Risk Index
Mapped soils that flood occasionally or frequently
1.1% USDA NRCS Web Soil Survey (SSURGO)
Hydric soils (a federal wetland indicator)
1.6% USDA NRCS Web Soil Survey (SSURGO)
Poorly or very poorly drained soils
1.1% USDA NRCS Web Soil Survey (SSURGO)
Surface water (lakes, rivers, reservoirs)
5 sq mi Census 2024 Gazetteer Files
Drought on 2026-10-27
100% moderate or worse, 87% severe or worse U.S. Drought Monitor county statistics

The floodplain share is the area FEMA's National Risk Index counts as exposed to inland flooding, mostly mapped 100-year flood zones. It says how common flood-prone land is in Franklin County, not whether a given parcel floods. For that, look up the zone at your exact point on the FEMA Flood Map Service Center or run the free check.

Soils and terrain

Prime farmland
0% USDA NRCS Web Soil Survey (SSURGO)
Prime only if drained, irrigated or protected
14% USDA NRCS Web Soil Survey (SSURGO)
Farmland of statewide importance
6% USDA NRCS Web Soil Survey (SSURGO)
Average slope over 15%
67% USDA NRCS Web Soil Survey (SSURGO)
Very limited for septic absorption fields
95% USDA NRCS Web Soil Survey (SSURGO)
Not limited for septic absorption fields
0% USDA NRCS Web Soil Survey (SSURGO)

Shares of Franklin County's soil-surveyed land (about 424,574 acres, open water excluded), using each map unit's dominant condition in USDA's SSURGO soil survey. Soils change within a few hundred feet, so the soil at your building site is what matters.

Farms and land use

Farms (2022)
727 USDA NASS, 2022 Census of Agriculture
Share of the county's land in farms
65% USDA NASS, 2022 Census of Agriculture
Average farm size
380 acres (median 62) USDA NASS, 2022 Census of Agriculture
Average value of land and buildings
$3,278 per acre, 16th lowest of 44 in Idaho USDA NASS, 2022 Census of Agriculture
Cropland
114,176 acres USDA NASS, 2022 Census of Agriculture
Pasture and rangeland
152,677 acres USDA NASS, 2022 Census of Agriculture
Woodland on farms
15,021 acres USDA NASS, 2022 Census of Agriculture
Irrigated land
50,893 acres USDA NASS, 2022 Census of Agriculture

Natural hazard ratings

FEMA's National Risk Index rates each hazard for Franklin County relative to every other U.S. county. Overall risk: Very Low.

  • Winter weatherRelatively Moderate
  • EarthquakeRelatively Low
  • LightningRelatively Low
  • WildfireRelatively Low
  • DroughtVery Low
  • HailVery Low
  • Heat waveVery Low
  • River and inland floodingVery Low
  • LandslideVery Low
  • Strong windVery Low
  • TornadoVery Low

FEMA National Risk Index, December 2025

Questions about buying land in Franklin County

How much of Franklin County, ID is in a flood zone?

About 2.1% of Franklin County's area is in the 1%-annual-chance (100-year) floodplain used by FEMA's National Risk Index (December 2025), 14th highest of 44 counties in Idaho. Whether a given parcel is in a flood zone depends on its exact location, so check the FEMA map at your pin.

How much does land cost per acre in Franklin County?

The 2022 Census of Agriculture put the average value of farm land and buildings in Franklin County at $3,278 an acre, 16th lowest of 44 counties in Idaho (the median Idaho county was $3,845). It's a self-reported average across farms, so small homesites and recreational tracts often sell for more per acre.

Will a septic system work on land in Franklin County?

Often, but test first. USDA soil surveys rate 95% of Franklin County's mapped soils very limited for conventional septic absorption fields, usually because of wetness, slow permeability, shallow rock or flooding. A perc or soil test on the parcel decides what system the health department will permit.

Is there good farmland in Franklin County?

0% of Franklin County's mapped soils are prime farmland, 14% are prime only if drained, irrigated or protected from flooding, and 6% are farmland of statewide importance (USDA SSURGO). The 2022 Census of Agriculture counted 727 farms averaging 380 acres.

How often is Franklin County in drought?

Since 2021, at least half of the county was in severe drought or worse in 42% of weekly U.S. Drought Monitor maps, and in extreme drought in 13%. On 2026-10-27, 100% of the county was in moderate drought or worse.

Can I check a specific property in Franklin County?

Yes. Enter the address or drop a pin anywhere in Franklin County on the free check. It shows which checks return data at that exact point, and the full report costs $29: flood zone, slope, soils, wetlands, roads, power lines, wildfire and more, each with its source. It is a screen of public maps, not a survey, title search or perc test.

Check the parcel, not just the county

County numbers tell you what to look for. The free check looks at your exact point in Franklin County: flood zone, slope, soils, wetlands, roads, power and more. The full report is $29.

Check a location in Franklin County

What these numbers can't tell you

  • County shares describe Franklin County as a whole; a parcel can be entirely in or out of a flood zone, wetland or poor soil.
  • It doesn't look at the whole parcel, its boundaries, title, easements, zoning or permits.
  • It isn't a survey, appraisal, elevation certificate, soil or perc test, or Phase I environmental site assessment.
  • It can't see local distribution power lines, driveways, legal access, wells or mineral rights.
  • Maps lag behind the ground, and distances are straight-line, not driving distance.

Sources and vintages

Summarized per county by our build script on 2026-10-31. County figures cover the whole county; checks on the report are at your point.