Small Wastewater (Septic) System Permit in Unincorporated Fremont County, Wyoming
VerifiedRequired for any new septic system installation, replacement, modification, or repair generating less than 2,000 gallons per day in unincorporated Fremont County. Fremont County holds delegated authority from the Wyoming Department of Environmental Quality (DEQ) to permit these systems under the Fremont County Small Wastewater Regulations — this is one of only two general land-development permit categories the county administers, since it has no county-wide building code.
Verified 2026-07-01 · Source
When you need this permit
- Required for any new installation, replacement of an existing system, or system repair
- A pre-permit conference with the county's Small Wastewater Specialist is recommended prior to purchasing property or beginning any development in areas with variable soil conditions
- Complete and submit the application packet, including percolation test results for the proposed leach field area, with the correct permit fee before any work begins
- A backhoe cut at least nine (9) feet deep is required where the absorption field is planned, for the site evaluation
- An Authorization to Construct is issued after site evaluation, before installation may proceed
- System must be inspected by the Small Wastewater Specialist prior to backfilling (48-hour advance notice appreciated)
- Systems generating 2,000+ gallons/day of residential waste, or any high-strength/commercial wastewater system, or any water supply system, are instead permitted directly by Wyoming DEQ (Northwest District Engineer)
- Any well proposed to supply water must be separately permitted through the Wyoming State Engineer's Office
Required documents
- Req
Small Wastewater Application Packet
Fremont County Planning Department application, including offset-distance requirements and percolation test instructions/forms
Fee schedule
| Fee type | Amount | Notes |
|---|---|---|
| New Standard Septic System (permit fee) | $650.00 | Fremont County Planning and Rural Addressing FY 2025 Fee Schedule, effective 7-1-2025 |
| New Nonconventional Septic System (permit fee) | $700.00 | FY 2025 Fee Schedule |
| New Commercial Septic System (permit fee) | $850.00 | FY 2025 Fee Schedule |
| Replacement Septic System (permit fee) | $600.00 | FY 2025 Fee Schedule |
| Modify System / Partial Replacement / Greywater (permit fee) | $500.00 | FY 2025 Fee Schedule |
| Surface Application of Septage (permit fee) | $750.00 | FY 2025 Fee Schedule |
| As-Built Septic System (permit fee) | $2,000.00 | FY 2025 Fee Schedule |
| Privy (permit fee) | $400.00 | FY 2025 Fee Schedule |
| Septic System Inspection Fee (for each inspection over two) | $200.00 | FY 2025 Fee Schedule |
Review timeline
3–21 business days
Unincorporated Fremont County’s published plan-review target
Inspection process
- 1
Site Evaluation
Small Wastewater Specialist evaluates the backhoe test cut (9 ft minimum depth) and percolation test results to size and configure the leach field
- 2
Pre-Backfill Inspection
System inspected by the Small Wastewater Specialist before backfilling; 48-hour advance notice appreciated
Tips
- Fremont County's own site states processing can take 'as little as a few days to as much as a few weeks depending on weather, construction delays and inspection schedules.'
- Septic system size is based on the number of bedrooms — if you plan to add space, move in a larger mobile home, or tie into an existing system, consider expanding the septic system to extend its life.
- The county provides copies of existing septic permits free of charge — useful when buying rural property to confirm system size/history.
- Contact the Small Wastewater Specialist BEFORE purchasing rural land or an existing septic system to discuss siting and compliance.
Frequently asked questions
- Who permits septic systems in unincorporated Fremont County?
- Fremont County Planning permits residential septic (small wastewater) systems generating less than 2,000 gallons/day, under authority delegated by the Wyoming Department of Environmental Quality. Larger or commercial high-strength wastewater systems, and all water supply systems, are permitted directly by Wyoming DEQ.
Sources & verification
Verified against official sources. Last reviewed 2026-07-01.
- Fremont County Planning Department — official building department
- Fremont County Planning Department — Wastewater Management
- Fremont County Planning and Rural Addressing FY 2025 Fee Schedule (effective 7-1-2025)
- Fremont County Planning Department — Building Codes & Certificates of Occupancy (confirms septic as one of the county's only two general permit categories)
Fees, timelines, and adopted codes are researched from each jurisdiction's published records — see how we verify. Requirements change and vary by project, so always confirm the current details with the Unincorporated Fremont County building department before you submit. PermitBase is an independent reference and is not affiliated with any government agency.
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