Kitsap County, WA Environmental Rules: Erosion Control (2026)
Key Facts
- Max slope without engineering
- 2:1 (horizontal:vertical)
- Engineered grading plan trigger
- 5,000+ cu. yd. or 1+ acre disturbed
- Minimum performance bond
- $5,000
- Alternate bond rate
- $10,000 per disturbed acre
- Grading-only permit validity
- 180 days from issuance
- Jurisdiction reached
- Unincorporated Kitsap County only
Summary
Unincorporated Kitsap County caps artificial slopes at a 2:1 gradient unless a professional engineer proves a steeper cut stays as erosion-stable as a properly maintained 2:1 slope. Grading of 5,000+ cubic yards or one acre or more of land disturbance requires an engineered grading plan and a site development activity permit before work starts.
(1) The maximum surface gradient on any artificially created slope shall be two feet of horizontal run to one foot of vertical fall (2:1). This gradient may be increased to that gradient which can be demonstrated through engineering calculations to be stable, if, in the opinion of the director, it has been demonstrated by the applicant through engineering calculations performed by a qualified professional engineer that surface erosion can be controlled to that erosion rate equal to a properly stabilized 2:1 slope under the same conditions.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: rev 4864424; v0 updated 2025-12-08; through 12-08-2025).
Full Breakdown
16 (Grading) governs erosion control on unincorporated construction sites. 030. 080(1) sets the core erosion standard: artificially created slopes cannot exceed a 2:1 (horizontal to vertical) gradient unless the applicant's engineer demonstrates through calculations, to the director's satisfaction, that a steeper slope will erode no faster than a properly stabilized 2:1 slope. 010 requires the owner to record a performance covenant or post a performance bond covering site stabilization and erosion and sedimentation control; Kitsap County-owned projects are exempt from this bonding requirement. 020, sites disturbing one acre or more must post a bond set at either 150% of the engineer's estimated cost of temporary erosion control and permanent stabilization (minimum $5,000), or a flat $10,000 per disturbed acre with no engineer's estimate required; the bond runs continuously with no expiration date until the county releases it.
030, which runs with the land until final county acceptance. 110 limits grading-only site development permits to 180 days from issuance, though work may be halted for weather. All of this applies only inside unincorporated Kitsap County; Bremerton, Port Orchard, Poulsbo and Bainbridge Island enforce their own separate grading and erosion codes within their city limits.
Violations & Fines
The county's department of community development enforces this chapter. If site work violates Title 12, KCC 12.16.060 makes an unstable excavation, embankment or fill a code violation once the director finds it hazardous to public safety, property, or a drainage channel. Under KCC 12.12.020, the county may draw on the posted performance bond to fund temporary and permanent stabilization itself; for covenant sites under KCC 12.12.030, the county can enforce the covenant directly, bill the project proponent for the stabilization costs, and record a lien against the property if the owner does not pay.
Frequently Asked Questions
Does unincorporated Kitsap County limit how steep I can grade a slope?
Do I have to post a bond for erosion control before I start grading?
How long does a Kitsap County grading permit last?
What happens if my erosion controls fail during construction?
Sources & Official References
Other rules in Kitsap County
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