Seattle regulates all grading and drainage activities under SMC Title 22 Subtitle VIII, requiring permits for excavation, fill, and changes to site drainage patterns to protect slopes, waterways, and neighboring properties.
Grading permits are required for excavation or fill exceeding specified thresholds, including cuts or fills deeper than 4 feet or involving more than 50 cubic yards of material. The Stormwater Code requires that post-development drainage patterns do not adversely affect neighboring properties. Projects must maintain predevelopment hydrology to the maximum extent feasible. Work on Environmentally Critical Areas such as steep slopes, wetlands, and riparian corridors requires additional geotechnical review and environmental mitigation. Seattle's terrain with significant grade changes makes grading regulation particularly important for slope stability and landslide prevention.
Unpermitted grading can result in fines up to $5,000 per day, stop-work orders, and mandatory site restoration. If unpermitted grading causes damage to neighboring properties or public infrastructure, the responsible party may face civil liability in addition to code enforcement penalties.
Seattle, WA
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Side-by-side rule comparisons with other cities in King County.
See how other cities in King County handle grading & drainage.
See how Seattle's grading & drainage rules stack up against other locations.
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