Kirkland, WA Environmental Rules: Erosion Control (2026)

KZC 115.35, Erosion and Sedimentation Regulation, is written as a strict standard: a property owner who creates, allows, or perpetuates a condition that erodes or undermines a neighboring lot, or that deposits sediment or other geologic material onto it, is in violation regardless of intent. The rule protects adjacent properties specifically, so conditions that stay entirely on the source parcel aren't reached by this section, though they may trigger other code provisions.

For active construction sites, the city layers on design-level erosion and sediment control requirements through Chapter 15.52 KMC, Surface Water Management. Under KMC 15.52.060(a), development must meet or exceed the thresholds in Appendix I of the Western Washington Phase II Municipal Stormwater Permit, and the city adopts the 2021 King County Surface Water Design Manual, the 2021 King County Stormwater Pollution Prevention Manual, and the City of Kirkland's own addendum to the county manual as the applicable standards. Developers and property owners are responsible for designing, constructing, and maintaining a system, commonly a temporary erosion and sediment control plan, that complies with those manuals, and the city inspects permanent drainage facilities before final permit approval.

Read together, KZC 115.35 supplies the after-the-fact violation for erosion that reaches a neighbor's land, while KMC 15.52.060 supplies the upfront design standard construction sites must follow to try to prevent it in the first place.