Bolthole Index

Lemhi County, Idaho

Building permits, zoning and land rules in Lemhi County, Idaho

64Index Score / 100
#17 of 44 in Idaho

Lemhi County, Idaho requires a building permit for construction, along with complete building plans and a plot plan; county projects also require a septic permit.1 The Lemhi County and City Building Department enforces adopted building codes and helps with land-use issues.2 Eastern Idaho Public Health handles septic applications, site evaluations, permits and inspections.3

At a glance

Building permit
Required for building construction in Lemhi County4
Zoning
County zoning applies; the Salmon Area of City Impact also follows the city code56
Septic
Permit and inspection through Eastern Idaho Public Health378
RV living
Private-land occupancy rule not confirmed; ask the Building Department9
Tiny home
No separate countywide tiny-home rule confirmed; zoning and building review still matter54
Owner-builder
Idaho homeowner exemption allows an owner to permit and perform work on a primary or secondary residence10
Minimum lot size
Varies with zoning, utilities, geography and groundwater conditions11
Private well
An IDWR drilling permit is required before drilling12

Who to call

Building permits

Lemhi County and City Building Department

County building permits, planning and zoning, adopted-code enforcement and land-use questions

208-742-1703

200 Fulton Street, Suite 204, Salmon, ID 83467

Septic permits

Eastern Idaho Public Health — Lemhi County Office

Onsite wastewater applications, site evaluations, septic permits and inspections for Lemhi County

(208) 756-2123

801 Monroe, Salmon, ID 83467

Contact details are copied from each office’s official page and were checked against it on September 27, 2026.

Do you need a building permit in Lemhi County, Idaho?

Yes. Lemhi County requires a building permit application, complete building plans and a plot plan for building construction, and a septic permit is required when building in the county.4 Work cannot begin and inspections will not be performed until the building permit has been issued.4

The county reviews construction drawings against its currently adopted codes and requires payment before issuing the permit.4 Idaho also requires separate permits when electrical, plumbing or HVAC work is performed, although the administering jurisdiction can vary by location.13

A qualifying agricultural building may receive a permit exemption only when it is used solely for eligible agricultural purposes and the Assessor determines the land is actively devoted to agriculture.14 That exemption does not cover human habitation, public use, repair shops or personal-vehicle garages and storage, and the building must still satisfy county placement plus applicable snow and wind standards.14

Who issues building permits in Lemhi County?

The Lemhi County and City Building Department handles county building permits from its office at 200 Fulton Street, Suite 204 in Salmon; call 208-742-1703.9 The department assists with land-use questions, checks compliance with existing regulations, enforces adopted building codes and provides emergency addressing.9

Start with the department before ordering plans because the required documents can depend on the project. Lemhi County’s core submittal is a permit application, complete building plans and a plot plan showing the proposed building location.4 The plot plan should be resolved before site preparation because county setbacks vary with road frontage, lot position, wall height and special locations such as stream corridors.15

The full inspection schedule for ordinary construction could not be confirmed. Ask the Building Department which inspections apply to the proposed work and when each must be requested.

Does Lemhi County have zoning?

Yes. The Lemhi County Development Code establishes zoning and overlay districts, and published standards vary by zoning district and planning area.516 Within the Salmon Area of City Impact, both the Salmon Development Code and Lemhi County Development Code apply, with the more restrictive provision controlling when they conflict.6

Lot size is not one countywide figure. Minimums vary with zoning, site characteristics, central water or sewer availability, groundwater vulnerability and named planning areas.11 Newly created lots require at least 110 feet of frontage; the code identifies a basic one-acre minimum but provides different minimums for serviced land and groundwater-vulnerability areas.11

County permit materials also specify setbacks and tell applicants to verify the applicable distance before preparing the site.15 A parcel review should therefore identify the zoning district, any overlay, legal lot status, access, utilities and the precise setbacks rather than assuming that rural acreage is unrestricted.

How do septic permits work in Lemhi County?

Eastern Idaho Public Health administers septic permitting in Lemhi County from its Salmon office at 801 Monroe; call (208) 756-2123.17 The district reviews wastewater applications, performs onsite evaluations, issues permits and conducts inspections.3

A valid installation permit is required before constructing, modifying or repairing an individual or subsurface sewage system, subject to limited exceptions for certain piping or mechanical repairs.7 An Environmental Health Specialist must inspect the installed system before it is covered, and a system covered prematurely must be uncovered.8

Soils deserve early attention: only about 4.4% of county soils are rated without severe limitations for a conventional septic drain field.18 Treat that as a screening signal, not a parcel verdict; the district’s site evaluation determines what can be permitted. Where public or central wastewater treatment is reasonably accessible, Idaho’s rules allow the permitting authority to deny an onsite septic permit.19

Can you live in an RV or tiny home in Lemhi County?

We could not confirm a general Lemhi County rule allowing or prohibiting temporary RV occupancy on private land. Before relying on an RV during construction, ask the Building Department how the parcel’s zoning district treats occupancy, whether a permit is needed and what approved sanitation must be in place.

A tiny home is not automatically outside the permit system. Lemhi County requires building permits for building construction and applies district-specific zoning standards.416 We could not confirm a separate countywide minimum dwelling floor area, so ask the Building Department to review the proposed structure, foundation, use and zoning district.

Manufactured or mobile homes used as permanent single-family dwellings are allowed only under stated conditions: qualifying construction standards, removal of the hitch, wheels, chassis and running gear, attachment to a permanent foundation, and permanent utility connections.20 Every manufactured-home installation must also be inspected and approved by the state or authority having jurisdiction before occupancy.21

Building a home in Lemhi County: what are the steps?

  1. Ask the Building Department to identify the zoning district, overlays, setbacks and required submittals for the parcel. County zoning and development standards vary by district and planning area.16
  1. Confirm that Eastern Idaho Public Health can approve an onsite wastewater system before fixing the house site. The district performs site evaluations and issues septic permits.3
  1. Resolve water. Idaho requires an IDWR drilling permit before a well is drilled, and wells must be constructed by an IDWR-licensed driller.12
  1. Prepare the building application, complete plans and plot plan, including the applicable setbacks and septic layout.415
  1. Obtain separate electrical, plumbing and HVAC permits for trade work.13
  1. Pay for and receive the building permit before starting work, then confirm the project-specific inspection schedule with the Building Department.4
  1. Keep the septic installation uncovered until the required health-district inspection is complete.8

What should you check before buying land in Lemhi County?

Start with buildability, not the listing description. Confirm the zoning district, overlays, legal access, applicable setbacks and whether the lot can support the intended use. Lemhi County regulates subdivisions, and each subdivision lot must accommodate a permitted use.22

Make septic feasibility an early contingency because only about 4.4% of county soils rate without severe limitations for a conventional drain field.18 The county is also steep overall, with about 28.4% of its land at a slope of 15% or less, so a parcel-specific house site, driveway and drain-field layout matter.23

Check flood status before designing. Development in a special flood hazard area needs a final as-built elevation certificate before the county issues a Certificate of Compliance or Occupancy.24 Confirm the water source and well-permit path with IDWR.12 Finally, budget around the countywide effective property-tax rate of about 0.4%, while verifying the actual parcel assessment and exemptions with the county.25

Watch-outs

  • Do not begin construction before the building permit is issued; Lemhi County says work and inspections cannot start earlier.4
  • In the Salmon Area of City Impact, both county and city development codes apply, and the more restrictive provision controls a conflict.6
  • A septic installation must remain uncovered until Eastern Idaho Public Health completes its required inspection.8
  • Private-land RV occupancy, the ordinary building-inspection schedule and a countywide minimum dwelling size remain unconfirmed; ask the Building Department before committing to a plan.9

Sources

  1. Building Department FAQs (2026 county census)
  2. Building, quoted and re-checked
  3. Septic, quoted and re-checked
  4. Building Department FAQs, quoted and re-checked
  5. Lemhi County Development Code, quoted and re-checked
  6. Lemhi County Development Code, quoted and re-checked
  7. Septic, quoted and re-checked
  8. Septic Permit Information Sheet, quoted and re-checked
  9. Lemhi County and City Building Department (lemhicountyidaho.org)
  10. Idaho Division of Building Safety - Homeowners (2026 county census)
  11. Lemhi County Development Code, quoted and re-checked
  12. Wells Overview (Idaho statewide rule), quoted and re-checked
  13. Frequently Asked Questions (FAQs) - Division of Occupational and Professional Licenses (Idaho statewide rule), quoted and re-checked
  14. Agricultural Building Permit Exemption, quoted and re-checked
  15. Lemhi County Building Permit Application, quoted and re-checked
  16. Lemhi County Development Code, quoted and re-checked
  17. Eastern Idaho Public Health — Lemhi County Office (eiph.id.gov)
  18. Share of soils without severe limits for a conventional septic drain field (USDA SSURGO): Bolthole Index county data
  19. IDAPA 58.01.03 Individual/Subsurface Sewage Disposal Rules (Idaho statewide rule), quoted and re-checked
  20. Lemhi County Development Code, quoted and re-checked
  21. Building Archives - Division of Occupational and Professional Licenses (Idaho statewide rule), quoted and re-checked
  22. Lemhi County Development Code, quoted and re-checked
  23. Share of land at 15% slope or less: Bolthole Index county data
  24. Lemhi County Development Code, quoted and re-checked
  25. Effective property tax rate: Bolthole Index county data

Written September 27, 2026 from the rules quoted below, each taken from an official source and re-checked by an independent reviewer. This is research, not legal advice: rules change, so confirm with the office before you buy or build.

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County locator

Lemhi County in Idaho

64
County map
Lemhi County highlighted among the Idaho counties · colored by Index score

How Lemhi County scores

Seclusion94100% ev.
Self-Sufficiency40100% ev.
Admin Boringness42100% ev.
Durability39100% ev.
Property Autonomy90100% ev.
Carry Cost77100% ev.

Evidence strength: 100%. This reports direct-source completeness and fallback use; it is separate from the score and is not a confidence interval. How it works →

$396kTypical home
0.4%Property tax
$3,947Land / acre
20.8"Annual rain
9.7% of yrsSevere drought
0.3 / yr (+0.3)Mid-century 100°F days
21.2 daysMid-century dry spell
1.11" (+6.7%)Mid-century 1-day rain
1.2×Wildfire change factor
100%Forward climate coverage
$1,713Home insurance / yr
4.3% / yrInsurance growth
0.99%Nonrenewal rate
county median (2+ published ZIPs)Insurance basis
174People within 30 min
898Radius comparison (15 mi)
1.8People / sq mi
90.9%Federal land
28.4%Land at 15% slope or less
4.4%Septic soil without severe limits
123,654 acWorkable land screen
49.2%Wooded land
23.3 tonsBiomass / forest ac
39.7°FAvg temp

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Answers from the rulebook for Lemhi County

What the ordinances and state agencies actually say — one answer per question, each quoted from the official source and independently re-checked.

Lemhi County rules

  • Building permitRequired

    Building construction in Lemhi County.

    • A building permit application, complete building plans, and a plot plan are required.
    • A septic permit is required if building in the County.
    • No work may commence before permit issuance.
    • Applicable construction drawings and currently adopted codes are reviewed; payment is required before issuance.
    “No work may commence, nor will any inspection be performed, prior to a building permit being issued so please plan accordingly.”
  • Building code adoptedAdopted

    Building-code enforcement by the Lemhi County and City Building Department.

    • The page does not identify a specific code edition.
    “Other functions of this department include the enforcement of adopted building code regulations, emergency 911 addressing, and providing assistance to other County and City Departments.”
  • Certificate of occupancyLimited

    Development in a special flood hazard area requiring a Certificate of Compliance/Occupancy.

    • A final as-built Finished Construction Elevation Certificate is required after construction and before issuance.
    • Deficiencies must be corrected before issuance; additional certification may be required.
    • Failure to submit certification or correct deficiencies may withhold issuance.
    “A final as-built Finished Construction Elevation Certificate (FEMA Form 86-0-33) is required after construction is completed and prior to Certificate of Compliance/Occupancy issuance.”
  • County-wide zoningPresent (with conditions)

    Land-use and zoning regulation under the Lemhi County Development Code.

    • The ordinance is enacted under Idaho’s Local Land Use Planning Act.
    • The Salmon Area of City Impact is subject to both the Salmon Development Code and Lemhi County Development Code; the more restrictive code applies.
    “This chapter creates zoning districts and overlay zoning districts based on the planning areas established in the comprehensive plan and adopts an official map of those districts.”
  • Local zoningVaries (with conditions)

    Aggregate county result for county-administered zoning and the Salmon Area of City Impact.

    • The conclusion aggregates county zoning with the documented Salmon municipal/city-impact overlay; the county does not administer every municipal ordinance.
    • Within the Salmon Area of City Impact both codes apply and the more restrictive code controls.
    “Within the area of City impact both the Salmon Development Code and the Lemhi County Development Code shall apply. If a conflict occurs, the more restrictive code applies.”
  • Zoning districtsPublished

    Zoning districts and district-specific development standards published in the Lemhi County Development Code.

    • The code identifies district-specific tables including Agricultural (A), Residential (R-1), Airport, and named geographic planning areas.
    • District standards vary by location and applicable water/sewer or groundwater conditions.
    “4.1. Zoning Districts. The following zoning districts are established to implement the comprehensive plan:”
  • Minimum lot sizeSpecified

    New development and lot creation under Lemhi County’s development code.

    • Minimum lot size varies by zoning district, geography, central water/sewer availability, and groundwater vulnerability areas.
    • All newly created lots must have at least 110 feet of frontage.
    • The table includes basic lots, central-water/sewer areas, groundwater-vulnerability areas, North Fork/Gibbonsville, and other named planning areas.

    minimum lot frontage: >= 110 feet · basic lot minimum: >= 1 acre (Central water or sewer areas: 1/2 acre; central water and sewer: 1/4 acre) · groundwater vulnerability area minimum: >= 2.5 acres (With central sewer: 1.5 acres; with central water and sewer: 1 acre)

    “There is a minimum lot size for any small-scale development. The minimum lot size may vary by zoning district or with the characteristics of the site, see table 6.5.”
  • SetbacksSpecified

    Building placement under the county building-permit application.

    • The application states the distances are examples and applicants should verify setbacks with the office before site preparation.
    • Different rules apply to existing lots in Elk Bend and Gilmore and to stream corridors and irrigation ditches.

    arterial-road setback: 25 feet · front-yard setback: 25 feet · corner-lot side-yard setback: 15 feet · rear setback: 10 feet for first 10 feet of wall height; 1:1 for greater heights · side setback: 10 feet for first 10 feet of wall height; 1:1 for greater heights

    “Setbacks For All Areas Setback From: Setbacks Distance (In Feet): Property line, arterial roads (measured from the edge of the road right of way) 25 feet Property line, front yard (measured from the edge of road right of way) 25 feet”
  • Manufactured homesAllowed (with conditions)

    Manufactured or mobile homes used as permanent single-family dwellings.

    • The home must comply with the National Manufactured Home Construction and Safety Standards Act or Building Code.
    • Hitches, wheels, chassis, and running gear must be removed and the home attached to a permanent foundation.
    • The home must be permanently connected to central or on-site utilities.
    “Includes both conventional dwellings and manufactured homes and mobile homes (rehabilitated under state requirements) that:”
  • Who permits septicLocal

    Septic regulation and permitting for Lemhi County through Eastern Idaho Public Health.

    • Eastern Idaho Public Health serves Lemhi County.
    • The program reviews applications, issues wastewater permits, and conducts inspections.
    “Review applications for disposing of waste water, Perform onsite evaluations, Issue waste water permits, Conduct inspections, Provide technical assistance and education to the public and those that install septic systems.”
  • Septic permitRequired

    Construction, modification, or repair of an individual or subsurface sewage disposal system in Lemhi County.

    • A valid installation permit is required before the activity.
    • Portable non-discharging systems may be used temporarily.
    • Repair of broken or clogged solid piping or electrical/mechanical malfunctions may be exempt if the system is not expanded without authorization.
    “It shall be unlawful for any person to cause or to perform the modifications, repair or construction of any individual or subsurface sewage disposal system within the State of Idaho unless there is a valid installation permit authorizing that activity.”
  • Septic inspectionRequired

    Permitted septic systems in Lemhi County.

    • Inspection by an Environmental Health Specialist is required before covering.
    • Systems covered before inspection must be uncovered.
    • Eastern Idaho Public Health requires 48 hours’ notice to schedule an inspection.
    “Final Inspection Mandatory: It is necessary to have the system inspected by an Environmental Health Specialist prior to covering in order to determine if the system was installed in accordance with the issued permit.”
  • Mandatory utility hookupConditional

    Subdivision and manufactured-home/recreational-vehicle-park development.

    • Subdivisions generally require electric power and telephone connections for each lot.
    • Remote or primitive subdivisions may be exempt if future utility easements are provided.
    • Manufactured-home/RV parks must be readily accessible to public or private water, sewerage, and electricity services.
    “electric power and telephone connections for each lot, including any extension of lines or cables required to serve the subdivision, in compliance with the standards established by the utility involved;”
  • Agricultural exemptionAvailable (with conditions)

    Qualifying agricultural buildings.

    • The building must be used solely for listed agricultural purposes.
    • The Lemhi County Assessor must determine the property is land actively devoted to agriculture under Idaho Code 63-604.
    • The exemption does not permit human habitation, public use, shops or machinery repair, or personal-vehicle garages/storage.
    • Agricultural buildings must still meet county placement standards and applicable snow and wind requirements.
    “The building is used solely for one or more of the purposes listed in subsection (1)(a) above; and b. The property on which the building is sited has been determined by the Lemhi County Assessor to be land actively devoted to agriculture.”
  • Subdividing landRegulated (with conditions)

    Subdivision of land for sale or development in Lemhi County.

    • Every lot must accommodate a permitted use.
    • Subdivisions in special flood hazard areas must comply with Chapter 9.
    • Irrigated-land subdivisions must demonstrate compliance with Idaho Code 31-3805.
    • Remote or primitive subdivisions may be exempt from electric and telephone connection requirements if future easements are provided.
    “This section regulates the division of land for sale and/or development, and provides additional performance standards subdivisions.”
  • Owner-builder exemptionAvailable

    Under Idaho's homeowner exemption a property owner may obtain the permit and personally perform all work on their own primary or secondary residence without a contractor license.

    Idaho Division of Building Safety - Homeowners ↗Scouted from the county site, not yet independently re-checked

Idaho rules that apply here

  • InspectionsRequired

    All manufactured-home installations in Idaho before the manufactured home is occupied.

    • The inspection and approval are performed by DOPL or the authority having jurisdiction.
    • Inspection and approval must occur before occupancy.
    “All installations must be inspected and approved by the Idaho Division of Occupational and Professional Licenses or the authority having jurisdiction before the manufactured home is occupied.”
  • Camping on your landLimited

    Camping or parking a vehicle or trailer on Idaho Fish and Game Wildlife Management Areas and access sites separate from a WMA.

    • The restriction applies in areas posted against camping or parking.
    • Leaving an unattended camp, vehicle, or trailer for more than 48 hours is prohibited without authorization.
    • Camping or parking for more than 10 days during any 30-day period on one WMA or one separate access site is prohibited without authorization.
    • The rule permits authorization by the Commission, Director, Regional Supervisor, or designee.

    unattended duration: > 48 hours (Unless specifically authorized by the Commission, Director, Regional Supervisor, or designee.) · camping or parking duration: > 10 days during any 30-day period per WMA or separate access site (Unless specifically authorized by the Commission, Director, Regional Supervisor, or designee.)

    “camp or park a vehicle or trailer for more than ten (10) days during any thirty (30) day period”
  • Accessory dwellingsLimited

    Accessory dwelling units for Idaho DEQ wastewater-flow and septic-system sizing purposes; this claim does not establish statewide zoning permission.

    • An ADU is sized as a single-family dwelling for the cited wastewater-flow guidance.
    • An ADU may combine flows with another structure into one system.
    • Any common septic tank must be large enough to hold the required capacity from both structures.
    • Local land-use, building, and septic authorities may impose additional requirements.

    wastewater flow basis: single-family dwelling

    “Size as a single family dwelling. Can combine with another structure's flows into one system”
  • Well permitRequired

    Construction or drilling of wells in Idaho, including domestic wells.

    • Before drilling, the well owner or driller must obtain a drilling permit from IDWR.
    • All wells must be constructed by a well driller with a valid IDWR license.
    • The separate water-right permit exemption for domestic purposes does not eliminate the drilling-permit requirement.
    • For new diversions in qualifying subdivisions filed on or after July 1, 2025, a water-right permit is required in a moratorium area, critical groundwater area, or groundwater management area, except for in-home uses and watering livestock.
    • Well construction rules apply to wells and other artificial openings more than 18 vertical feet below land surface.

    well depth threshold: > 18 vertical feet below land surface (The cited well-construction rules describe covered wells and artificial openings.) · subdivision application date: >= 2025-07-01 (Applies to qualifying new diversions described in Idaho Code § 42-227(4).)

    “Prior to drilling a well, the well owner or well driller must first obtain a drilling permit from IDWR.”
  • Driveway accessRequired

    Private and public driveways or streets connecting to Idaho state highway right-of-way.

    • An ITD encroachment permit is required for private and public approaches, including driveways and streets.
    • No activity may occur on state highway rights-of-way until the Department or a delegated local highway agency issues an approved permit, except emergency approval affecting highway operations and motorist safety may precede processing.
    • A Traffic Impact Study may be required for new or expanded development seeking direct access to a state highway when the stated thresholds are met, unless waived by the District Engineer.

    peak-hour trips for possible TIS requirement: >= 100 new trips (unless waived by the District Engineer) · daily traffic for possible TIS requirement: >= 1000 vehicles per day (unless waived by the District Engineer)

    “Encroachment permits approved by the Department are required for private and public approaches (driveways and streets), utilities and other miscellaneous encroachments.”

Still unanswered

We looked and could not find an official answer yet. Silence is not permission — ask the county directly.

  • Minimum dwelling size — Minimum floor area for dwellings in Lemhi County.
  • Off-grid sanitation — Off-grid sanitation systems in Lemhi County.
  • Short-term rentals — Short-term or vacation rentals in Lemhi County.
  • Permit fees — County building-permit fees.

Each answer was extracted from an official source and independently re-checked against that source by a second reviewer. That is an evidence check, not legal advice. Rules change; confirm with the authority before you buy or build.

Living off-grid in Lemhi County, Idaho

Is Lemhi County a good place to live off-grid or homestead?

Lemhi County scores 64/100 on the Bolthole Index, a strong county profile. Its strengths: deep seclusion — about 174 people within a 30-minute drive and a stronger property-autonomy legal backdrop. Watch-outs: elevated current hazard exposure and thin water margin (20.8″/yr rainfall).

Do you need a building permit in Lemhi County, Idaho?

Lemhi County generally requires a residential building permit, and it enforces county zoning. Onsite septic is permitted by Eastern Idaho Public Health. Owner-builders may act as their own contractor to build their home. These answers are quoted from official sources and independently re-checked. Rules change and cities within the county differ — always confirm with the county before you buy or build.

How much does land cost in Lemhi County, Idaho?

Land in Lemhi County runs about $3,947 per acre, based on the latest county data.

What is the water situation in Lemhi County?

Lemhi County gets about 20.8" of rain a year, with severe drought in roughly 9.7% of years.

How remote is Lemhi County?

A typical private-land location has about 898 people within 15 miles and 289,398 within 100 miles. These radius catchments are the published fallback where road routing is unavailable.

Off-grid gear

Going off-grid in Lemhi County means bringing your own water and power. The kit we’d start with:

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How Lemhi compares in Idaho

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