Grading & Drainage Permit in Unincorporated Ada County, Idaho
Required for grading and drainage work in unincorporated Ada County. Three tiers apply based on the area of disturbance and project type: Tier 1 for residential grading under one acre, Tier 2 for disturbance of one acre or more, and Tier 3 for commercial projects and new subdivisions. Governed by the 2018 International Building Code and Ada County Code (ACC 8-6). Applications submitted digitally by email.
Verified 2026-06-29 · Source
When you need this permit
- Tier 1 (residential, area of disturbance less than 1 acre): site plan/drainage plan with property lines, easements, structures, well/septic locations, area of disturbance, stormwater flow arrows, and narrative
- Tier 2 (disturbance 1 acre or greater): all Tier 1 items plus plan prepared by a design professional; soils report may be required
- Tier 3 (commercial/drainage projects, new subdivisions): detailed drainage plan drawn to scale with all grading, drainage system essentials, stormwater routing, discharge flows, and evidence of consent from affected irrigation/drainage entities
- Submit Grading & Drainage Application with all required documents to mechanical@adacounty.id.gov
Required documents
- Req
Grading & Drainage Application (2025)
Ada County grading/drainage permit application listing all submittal requirements by tier; available at adacounty.id.gov/developmentservices/permitting-division/applications-forms-templates/
- Req
Site Plan / Drainage Plan
Required for all tiers — must show property lines, easements, existing structures, well/septic locations, area of disturbance, stormwater flow direction
- Opt
Design Professional Drainage Plan (Tier 2 and Tier 3)
Tier 2: prepared by a design professional. Tier 3: full drainage plan drawn to scale with calculations; soils report may be required
Fee schedule
| Fee type | Amount | Notes |
|---|---|---|
| Tier 1 — Residential grading, area of disturbance less than 1 acre | $100.00 | Ada County Grading & Drainage Application (2025) |
| Tier 2 — Area of disturbance 1 acre or greater | $500.00 | Ada County Grading & Drainage Application (2025) |
| Tier 3 — Commercial grading/drainage projects, new subdivisions | $1,500.00 | Ada County Grading & Drainage Application (2025) |
Review timeline
~5–21 business days
Typical estimate — confirm current times with the Unincorporated Ada County building department
Inspection process
- 1
Erosion Control (pre-grading)
Erosion control measures must be in place before work begins
- 2
Final Grade
Drainage verified, slopes stabilized, and grading matches approved plan
Tips
- Ada County's contact for grading/drainage questions is 208-287-7947 (Benjamin Pavelka, Permitting Manager).
- Tier 2 drainage plans must be prepared by a licensed design professional; soils reports may be required at the reviewer's discretion.
- For Tier 3 projects, provide documentary evidence of consent from all affected irrigation and drainage entities with rights to facilities on the site (ACC 8-6).
- Call 811 before any excavation to locate underground utilities.
Frequently asked questions
- Do I need a grading permit for my residential property in unincorporated Ada County?
- If you are disturbing less than one acre on a residential property, you need a Tier 1 Grading/Drainage Permit ($100). Projects disturbing one acre or more require a Tier 2 permit ($500) with a design-professional-prepared drainage plan. Submit the Grading & Drainage Application to mechanical@adacounty.id.gov. Source: Ada County Grading & Drainage Application (2025).
Sources & verification
Verified against official sources. Last reviewed 2026-06-29.
- Ada County Development Services — Building Division — official building department
- Grading & Drainage Application (2025) — PDF | Ada County Development Services
- Applications, Forms, and Templates | Ada County Development Services
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 Ada County building department before you submit. PermitBase is an independent reference and is not affiliated with any government agency.
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