10 county-level rules, plus city-specific rules for 8 cities in King County, Washington.
Verified from official government sources
Stormwater in King County is regulated under KCC 9.04 and the Surface Water Design Manual. Projects adding 2,000 sq ft of impervious surface or clearing 7,000 sq ft trigger review. NPDES MS4 permit applies.
Erosion control in King County is regulated under KCC 16.82 and the Surface Water Design Manual. Clearing over 7,000 sq ft or grading over 50 cubic yards requires a permit with BMPs and wet-season rules.
Unincorporated King County's marine shoreline along Puget Sound and Vashon-Maury Island is regulated under the Shoreline Management Act (RCW 90.58), the King County Shoreline Master Program (K.C.C. Title 21A), and the Critical Areas Ordinance at K.C.C. Chapter 21A.24. Shoreline jurisdiction extends 200 feet inland from the ordinary high water mark. Critical-area buffers along marine shorelines are typically 115 to 165 feet.
Floodplain development in King County is regulated under KCC 21A.24 and FEMA NFIP. SFHAs require elevated construction to BFE plus 1 foot freeboard, flood vents, and development permits.
Grading and drainage in King County are governed by KCC 16.82 and the Surface Water Design Manual. Grading over 50 cubic yards or affecting critical areas requires permits and drainage review.
King County and Washington state limit unnecessary diesel idling, particularly near schools, hospitals, and Metro bus bases, to protect air quality in the central Puget Sound airshed.
King County itself does not ban gas-powered leaf blowers countywide, but several cities including Seattle are phasing out gas blowers, and noise rules in KCC 12.86 apply to all power equipment.
King County's Strategic Climate Action Plan, updated in 2020, sets a binding countywide goal of carbon neutrality by 2050 with a 50% reduction by 2030 from a 2007 baseline.
King County encourages cool roofs and reflective surfaces through the Washington State Energy Code and green building incentives, especially for large commercial reroofs in unincorporated areas and Metro facilities.
King County addresses urban heat islands through tree canopy goals, cool surfaces, and equity-focused investments under the Strategic Climate Action Plan and the 30-year Land Conservation Initiative.
8 cities in King County have their own environmental rules rules. Each link goes to that city's dedicated page with code citations.
14 verified rules • Boat Dock Permits, Climate Emergency Mobilization
4 verified rules • Erosion Control, Flood Zones
4 verified rules • Erosion Control, Flood Zones
4 verified rules • Erosion Control, Flood Zones
6 verified rules • Boat Dock Permits, Erosion Control
4 verified rules • Erosion Control, Flood Zones
4 verified rules • Erosion Control, Flood Zones
4 verified rules • Erosion Control, Flood Zones
See every category we cover for King County — parking, noise, fences, fires, animals, pools, and more.
King County Ordinance Hub →