Septic / Small Wastewater System Permit in Unincorporated Sheridan County, Wyoming

Unincorporated Sheridan County requires a septic / small wastewater system permit for: Covers conventional systems only: wastewater flow under 2,000 gallons/day of domestic sewage, standard trench/bed disposal (stone-and-pipe or chambers), seasonal high groundwater/bedrock/impervious clay 4+ feet below the proposed leachfield bottom, and soil percolation rate between 5 and 60 minutes per inch; Non-conventional systems (outside those parameters) require direct consultation with Sheridan County Public Works; systems over 2,000 gal/day or non-domestic waste route to the WY DEQ Underground Injection Control (UIC) Program; Groundwater test pit dug 4 feet deeper than the bottom of the proposed leachfield, open at least 24 hours, and inspected by a Sheridan County representative prior to submission; Percolation test performed per county instructions; Proof of ownership (recorded deed) required; notarized authorization needed if applicant is not the owner; 24-hour notice required to schedule the final inspection prior to backfilling the system; Fee due upon submission; starting installation before approval is subject to a fine. If your project isn't listed, confirm with Sheridan County Public Works Department (Planning / Building Official) at (307) 674-2920 or (307) 675-2420 before starting work.

In Unincorporated Sheridan County, the published Septic permit fee (due upon submission) is: $250.00. These are the jurisdiction's own published figures — see the fee schedule table and source citations on this page.

Plan review for a septic / small wastewater system permit in Unincorporated Sheridan County typically runs 5–20 business days. This is an estimate, not a published figure — confirm current review times with Sheridan County Public Works Department (Planning / Building Official) at (307) 674-2920 or (307) 675-2420.

You'll need: Septic System Permit Application (Sheridan County / WY DEQ design forms, Water Quality Division). See the required-documents checklist on this page for details on each.

Unincorporated Sheridan County requires 2 inspection(s) for a septic / small wastewater system permit, in order: Groundwater Test Pit Inspection, Final / Backfill Inspection. Schedule each through Sheridan County Public Works Department (Planning / Building Official) ((307) 674-2920 or (307) 675-2420).

Apply through Sheridan County Public Works Department (Planning / Building Official) at 224 South Main Street, Suite 428, Sheridan, WY 82801. Phone: (307) 674-2920 or (307) 675-2420, email: publicworks@sheridancountywy.gov. Office hours: Mon–Fri 8:00am–5:00pm (Sheridan County general office hours per the sheridancountywy.gov site footer, re-confirmed 2026-07-16; not separately published as Public-Works-specific hours). Official information: https://www.sheridancountywy.gov/departments/planning/building_in_the_county/index.php.

Unincorporated Sheridan County, Wyoming has adopted: NO countywide building code / NO general building permit for private construction in unincorporated Sheridan County. Per the Wyoming State Fire Marshal's 'Local and State Jurisdictions' chart, Sheridan County (county-level row) is listed BLDG INSP/PR = STATE and ELEC INSP/PR = STATE — the county has NOT taken general countywide building-code delegation under W.S. § 35-9-121, so the State Fire Marshal / state program has building and electrical jurisdiction across most of unincorporated Sheridan County.; IMPORTANT NUANCE (confirmed on the county's own site): Sheridan County DOES have an adopted 'Building Standards, Sheridan County, Wyoming' rule (adopted Nov. 18, 1991; last amended May 16, 2023, filed as County Clerk doc. #2023-785780) that adopts the 2021 International Building Code, 2021 IRC, 2021 IMC, 2021 IFGC, 2021 IPC, 2021 International Fire Code, the 2022 National Electrical Code, and the Uniform Code for the Abatement of Dangerous Buildings — but ARTICLE I, Section 3 (Applicability) confirms this code applies ONLY within a mapped 'Sheridan County Building Standards Area' (a defined zone around/adjoining the City of Sheridan shown on the Appendix A Planning Map), PLUS specific legacy subdivisions the BOCC imposed permitting/inspection on before Dec. 5, 2006, all NEW subdivisions approved after Dec. 5, 2006, and any structure built under a Conditional Use Permit. It does NOT apply countywide.; Farms and ranches on 40 acres or more of deeded land are specifically EXEMPT from the Building Standards code entirely (Article I, Sec. 3(b)(1)), as are county hospitals, mines/oilfield/refinery facilities, and railway buildings.; Where the Building Standards DO apply (the mapped area / qualifying subdivisions / CUP structures): a building permit is required before construction of any building/structure valued over $5,000 (Article III, Sec. 1), enforced by the Sheridan County Building Official.; Where the Building Standards do NOT apply (the vast majority of unincorporated Sheridan County — rural and agricultural land outside the mapped area): there is no county building permit for private construction; a Zoning Permit (land-use/setback compliance, not a structural building-code permit) is still required countywide for new construction or change of use.; Electrical: wiring permits/inspections are issued by the Wyoming State Fire Marshal's Office — Dept. of Fire Prevention & Electrical Safety (Chief Electrical Inspector), not Sheridan County, per the county's own Zoning Permit application which directs applicants doing new electrical work to WSFM..

Sheridan County Public Works issues septic/small wastewater permits countywide, following design standards aligned with Wyoming DEQ Water Quality Rules and Regulations Chapter 25. The fee is $250, due at submission.