Small Wastewater (Septic) System Permit in Unincorporated Fremont County, Wyoming

Unincorporated Fremont County requires a small wastewater (septic) system permit for: 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. If your project isn't listed, confirm with Fremont County Planning Department at (307) 332-1077 before starting work.

In Unincorporated Fremont County, the published New Standard Septic System (permit fee) is: $650.00. Additional published fees: New Nonconventional Septic System (permit fee) — $700.00; New Commercial Septic System (permit fee) — $850.00; Replacement Septic System (permit fee) — $600.00; Modify System / Partial Replacement / Greywater (permit fee) — $500.00; Surface Application of Septage (permit fee) — $750.00; As-Built Septic System (permit fee) — $2,000.00; Privy (permit fee) — $400.00; Septic System Inspection Fee (for each inspection over two) — $200.00. These are the jurisdiction's own published figures — see the fee schedule table and source citations on this page.

Unincorporated Fremont County's published plan-review target for a small wastewater (septic) system permit is 3–21 business days.

You'll need: Small Wastewater Application Packet. See the required-documents checklist on this page for details on each.

Unincorporated Fremont County requires 2 inspection(s) for a small wastewater (septic) system permit, in order: Site Evaluation, Pre-Backfill Inspection. Schedule each through Fremont County Planning Department ((307) 332-1077).

Apply through Fremont County Planning Department at 450 North 2nd Street, Lander, WY 82520. Phone: (307) 332-1077, email: support@fremontcountywy.gov. Office hours: Mon–Fri (contact department for current hours). Official information: https://fremontcountywy.gov/government/departments/planning_department/building_codes.php.

Unincorporated Fremont County, Wyoming has adopted: NO county-wide building code and NO county-specific building permit for private construction. Fremont County's own Planning Department page states verbatim: 'Fremont County does not have any County-wide Zoning or County specific Building Codes, except the following' (small wastewater/septic permits and floodplain zoning in mapped FEMA hazard areas near Lander, Riverton, Dubois, and Hudson) — https://fremontcountywy.gov/government/departments/planning_department/building_codes.php; Confirmed against the Wyoming Dept. of Fire Prevention & Electrical Safety 'LOCAL AND STATE JURISDICTIONS' chart (updated 7/7/2026 as of this check — the date label itself changed from a prior 5/11/2026, but the underlying Fremont County determination did not — embedded at wsfm.wyo.gov/electrical-safety): Fremont County's BLDG INSP/PR and ELEC INSP/PR columns are both still marked S/S (state) for the unincorporated county, meaning the county has NOT taken general building-code delegation under W.S. § 35-9-121 — the State of Wyoming, not Fremont County, has building jurisdiction over unincorporated private construction; Fremont County's own building-codes page RECOMMENDS (does not require) that residents follow the State of Wyoming's adopted codes for new construction: 2024 International Building Code, 2024 International Existing Building Code, 2024 International Mechanical Code, 2024 International Fire Code, 2024 International Fuel Gas Code, and the National Electrical Code (2023 edition was in effect through June 30, 2026; per wsfm.wyo.gov/electrical-safety, the 2026 NEC edition took effect statewide July 1, 2026) — these are recommendations for quality/insurability, not a locally enforced code, and the county issues no building permit and performs no building inspection against them; Fremont County explicitly states it does NOT issue Certificates of Occupancy; Commercial/public construction is NOT fully unregulated: per Wyoming Statute § 35-9-108, a State Fire Marshal plan review IS required for government/school buildings, buildings over 5,000 sq ft with public access, childcare centers (10+ children), multi-story buildings, places of assembly, fire-protection-system work, alternative energy installations (solar/wind/generator), aboveground flammable/combustible liquid storage tanks, Type I commercial kitchen hoods, spray finish applications, and RV/camping/mobile-home park site plans — contact the State Fire Marshal's Plan Review office (Jeff Schoen, (307) 673-1461, jeff.schoen@wyo.gov) for any of these commercial scopes; The Incorporated Cities within Fremont County (Riverton, Lander, Dubois, Hudson, Shoshoni, Pavillion, and South Pass City) each have their OWN separate zoning and building codes and issue their own permits — this LEAN page covers ONLY unincorporated (outside city-limits) Fremont County. See the separate City of Riverton page for Riverton's own building department.. Local amendments apply — see the Unincorporated Fremont County overview page for the full list.

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.